stout beer

Freezing beer, if it even worked, would be more trouble than it was worth. And I think it actually doesn't work anyway.

Finding someone who'll volunteer to drink the rest shouldn't be too difficult. ?

I bet it will work just fine for that purpose...I'd measure out batch sized portions, cover, and freeze.  I've certainly had plenty of frozen and then thawed cans of beer before and they weren't completely ruined (and nothing that would be detectable using it as an ingredient in bread).

And while it will lose it's carbonation, a growler of beer in the fridge won't 'go bad' (as in growing mold or funky bacteria) for quite a while, so you might just experiment with that, giving it the sniff test as you go.  I've saved extra amounts of stout for a couple weeks in the fridge to put in multiple batches of Rugbrod and it worked well.

No