this game has a mandatory button straddle and i'm in the 50 restraddle UTG, UTG+1 restraddles to 100, four limpers to me, i complete with 5432hhss, UTG+1 checks

i have ~7k and UTG covers

flop (600) A26

i check, UTG bets 200, two callers to me and i call

turn (1400) 4

i pot, UTG calls fairly quick, other limper folds

UTG is generally a big loser who steams easily, plays too many hands, makes and pays off with a lot of 2nd best draws, and bluffs too much. however, he is capable of playing pretty decent for stretches and has been pretty ABC / tight tonight, and is up a lot. he views me as very solid and pretty tight.

river (4200) A

i check, he pretty quickly breaks off a stack of blacks without counting and bets 1900.

I call. He prob has it but you only need to be good 25% of the time.

Unblock clubs, block A4 and A2

Pay the man

You have the perfect hand to call with blocking boats. I snap call.

Is the restraddle mandatory as well? If not, why do it?

The 'break off seemingly random amount of chips out of your stack' move seems reasonably-well distributed between value and bluffs, but I suspect a slight tendency towards value, as bluffs need to be given more consideration as to sizing in order to be successful; however that's easily balanced by just knowing ahead of time roughly what's in each stack. I would call because: good odds; blocking some boats; he views you as capable of laying hands down; he's winning decently; enough missed draws he can have; small chance (~10-15%?) of him valuebetting a worse hand like AK.

If this is a private game there could be political reasons; even in a casino game that isn't semi-private, there could be political reasons such as keeping gambly fish happy, who might otherwise leave if you don't gamble with them by making gestures like restraddles.

I would think if the villain has two pair or a set on the flop he'd bet bigger - would snap this off.

Flop bet feels like a draw tbh. Calling river. Personally I’m trying to check raise turn.