I have logic. I'm not saying the Mosin is a better weapon than the AR or AK or SKS ect ect. Im saying it would work for SHTF purposes.
I gotta chime in in defense of MO on this. And, I don't even have a Mosin. Not opposed to them, certainly, will probably acquire one as time marches on. But, I'm certainly not a Mosin fanboi.
To paraphrase the OP, the main criteria is for a gun/guns that non-gun people can readily use. So, do we really want some gun n00b messing around with uber tactical EBRs? Probably not. I would look for something simple, reliable, and effective - probably in that order. Plus, with a Mosin, at some point, they could probably "field requisition" an upgrade.
On a related note, I'd not buy the guns for them.* They'd have no skin in the game. I'd do the same thing I'd do for anyone else looking to buy a gun - figure out what you want to do with it, then how much money you want to spend. Since this is the SHTF forum, I'd probably also borrow from the "Guns Every Gun Owner Should Have" thread and tell them to get a "big boy" rifle, a pistol, a shotgun, and a .22 rifle.
For rifles, particularly for those that are short on cash, I'd put the Mosin on the list. I'd probably push towards SKS/AK/AR platforms, but any WWII era rifle would be on the list, too. Of course, I would also caution that if they get too wacky with ammo type, it will get harder to help them out. If they want to go for .404 Ultra Super Hopped Up Hollow Points ++ stuff, then dey be on dey own.
Also, just a thought here... maybe train BEFORE SHTF?
Really, I think the conversation about "Hey can you get us some guns" could really be turned more into a "Sure, but before we do that, how about let's go to the range and figure out what works for you duffs." If they aren't gun-types now, that sort of thing can help get them there, at less of a cost to you!
(Also, apologies if this was covered earlier up-thread. I didn't read the whole danged thing.)
* If this was some sort of quid pro quo, where some other guy was responsible for food, another for generator and fuel, etc., I might consider it. Otherwise, I would want them to undertake the investment.