Well, if he is LAGG, why not re-raise preflop and play HU having premium hand against usual lagg's crap?

Ok, you decided to flat call and see the flop. It's fine too.

It's 25BB pot plus another 25BB PSB, pot control will be really hard here, flat call makes it 75BB and you have only PSB left for 2 streets. Even minraising gets that hand to its pressure point, you can't control the pot here.

Against nit it's insta-muck unless nit can laydown overpairs on scary boards. Then you can bluff him with outs because you'd be against better overpair 90% of the time (nits don't c-bet PSB missed overs against 3 opponents).

But the opponent is loose aggressive and real postflop nutcase, never slows down, play it for stacks with him for value. You have most likely the best hand and some outs against set/better overpair. Drop the hammer.