Not universally true - it depends on the department. Even in departments that allow personally acquired weapons, requirements for firing pin blocks and/or exclusion of cocked and locked single actions are not unheard of.
I think he was referring to
his department.
I was at the JFK Federal Building about a month ago and I noticed an armed guard carrying a Ruger Wheel Gun. I was taken back by it and was surprised there are still guys (although few) who prefer the low capacity and high reliability of wheel guns. Gun looked great but I'd hate to see the poor bastard in a shootout.
Security companies can be weird. I worked for one place that only allowed regular guards to carry 9mm or .40, but supervisors could carry any caliber, so long as they could use Federal Hydrashok or EFMJ ammo in it.
Another thing to keep in mind is that a lot of companies out in Boston have guys working as "Boston Specials" (security guards with special police powers on their property). Under Rule 400, Boston specials can only carry .38 revolvers, so the company sets that as their policy, even if the guard isn't a "Boston Special," even if they don't work in Boston.
But the biggest thing with most guys is price. You can pick up a used duty sized revolver for a lot cheaper than a semi (in most cases), so guys will go cheap to meet the minimum requirement to work. I've worked with guards who carry guns that they loaded out of the box and never fired...guns that they clean once per year, even after multiple range days and time spent in the rain...damaged guns that don't work right due to their finances...and in one case, a guy with warrants for his arrest was carrying a gun without a license, while working as a security guard. People are people, and just because the job requires a gun doesn't mean they're a gun guy.
Each police department sets different rules and policies in place for their officers, rules that are often written by people without being thought through. I know of a PD in Mass. that doesn't allow officers to take their duty weapon home, so at every shift change, there's two shifts of cops loading and unloading their guns in the station, per department policy.
There's still PD's in the US that only issue a pistol and handcuffs, no baton, OC, taser or other force options, just arrest them or shoot them.
Other departments issue the cheapest guns and holsters they can find to save money, putting cops lives at risk in every situation they're in.
Think of it this way. The duty weapon policies of Mass. police departments are as varied and as confusing as the LTC issuing policies of Mass. police departments.