Good River bet-fold or call it off? Online zoom .02-.05, 6 handed.

V opens utg to .20, hero calls in BB with As4s.  This feels standard.

(.42)  Flop is Ad6h9c. Hero checks V bets .20, hero calls.  Also standard.

(.82)  Turn 8h, hero checks, V checks.

(.82). River Ks.  Hero leads for .60, V ships it for 2.20 total (1.60 more). I tank fold.  V's line makes sense for KK and K9s only (if V even opens K9s), but it's hard to come up with natural bluffs.  Thoughts?