Rob,
You've touched on a common problem when dealing with the police in a number of matters. You find the same problem with a towed car. Most often, the police contact an independant towing company, and at that point the police are removed from liability.
Here are some points that you have in your favor:
Chapter 140 Section 129 - D
Such person, or his legal representative, shall have the right, at any time up to one year after said delivery or surrender, to transfer such firearms, rifles, shotguns and machine guns and ammunition to any licensed dealer or any other person legally permitted to purchase or take possession of such firearms, rifles, shotguns and machine guns and ammunition and upon notification in writing by the purchaser or transferee and the former owner, the licensing authority shall within ten days deliver such firearms, rifles, shotguns and machine guns and ammunition to the transferee or purchaser and due care shall be observed by the licensing authority in the receipt and holding of any such firearm, rifle, shotgun or machine gun and ammunition.
By law, you can file a request with the authority to have the firearms transfer (limited to an FFL in the case of a 209A issue) and the licensing authority has 10 days to comply with that order. Ideally, you have this request written up ahead of time and an FFL prepared to recieve them, so that in the event that something happens, the 10 day clock can start ticking immediately. Also, legally, the PD does have a responsibility to ensure "due care" it provided for the firearms in reciept or holding. - A very difficult civil lawsuit, but the law does spell out that liability for due care.
The licensing authority, after taking possession of any firearm, rifle, shotgun, machine gun or ammunition by any means, may transfer possession of such weapon for storage purposes to a federally and state licensed dealer of such weapons and ammunition who operates a bonded warehouse on the licensed premises that is equipped with a safe for the secure storage of firearms and a weapon box or similar container for the secure storage of other weapons and ammunition;
They have the right to transfer them to a dealer or bonded warehouse for storage, but that doesn't absolve them of their resposibilities to comply with the previous paragraph, to transfer them per your request within 10 days.
Any such dealer that takes possession of a weapon under the provisions of this section shall: (i) inspect such weapon; (ii) issue to the owner a receipt indicating the make, model, caliber, serial number and condition of each weapon so received; and (iii) store and maintain all weapons so received in accordance with such regulations, rules or guidelines as the secretary of the executive office of public safety may establish under this section.
The dealer recieving the firearms has an obligation to the owner to issue a receipt of the firearms, including current condition. Legally, this is the dealers responsibility, not the PDs.
The owner shall be liable to such dealer for reasonable storage charges and may dispose of any such weapon as provided under this section by transfer to a person lawfully permitted to purchase or take possession of such weapon.
The owner is liable to the dealer for storage charges, which must be "reasonable" - another difficult legal battle, but if you can produce 3-4 quotes for storage by other dealers in your area - including 1 you have an order to transfer it to, you should be able to make a reasonable claim that a specific storage charge is "unreasonable" - but the owner still has the legal right to require that the recieving dealer (bonded warehouse) dispose of them per the owners requirements. Again, if this is a 209A issue, that transfer may only be to a licensed dealer.
Any such weapon that is stored and maintained by a licensed dealer as provided under this section may be so auctioned at the direction of: (i) the licensing authority at the expiration of one year following initial surrender or delivery to such licensing authority; or (ii) the dealer then in possession, if the storage charges for such weapon have been in arrears for 90 days; provided, however, that in either case, title shall pass to the licensed dealer for the purpose of transferring ownership to the auctioneer; and provided further, that in either case, after deduction and payment for storage charges and all necessary costs associated with such surrender and transfer, all surplus proceeds, if any, shall be immediately returned to the owner of such weapon..
Even if the firearms are transfered to a dealer, the dealer can't dispose of the firearms until the earlier of: 1 year from surrender or 90-days of lack of payment of storage fees, and then only if the owner has not disposed of them per the previous paragraphs. The means, immediately request a written quote of the storage fees and be prepared to pay for 10 days worth of storage (Fight the rate as unreasonable after the firearms have been transfered) and get the firearms transfered to a friendly dealer ASAP.
Keep in mind, that all of these are up-hill legal battles because you're "the bad guy" (you were served with a Protective Order - that makes you a bad guy) and you're asking the court to assign liability for your property to the good guys (the police who are just trying to protect the public from the bad-guy) but at least know when and where the letter of the law is on your side.