Please understand that this is just my opinion so take it for what it is worth. I do not believe a ban is imminent, I think most Dems in the Congress/Senate remember what happened to their predecessors after the Clinton ban, and don't want to suffer the same fate. The second reason I fell we MA residents should avoid panic buying, is that we still live under the ban. Unless a renewed ban is proposed that is far worse in nature then the '94 ban, nothing changes for those of us behind the iron curtain. If you feel the need to cover your six go buy one, if you are willing to risk waiting for the hype to die down, it may be worth it. As far as buying a stripped lower goes, for a firearm to be considered pre-ban in '94, it had to be a complete rifle before the ban. Of course you will be the only one who will know the exact date you made it into a complete rifle so the deck is kind of stacked in your favor if you are willing to bend the truth.
So in summary I would wait it out, but that is easy for me to say as I already have my AR(s).