Are you sure it does? I'm looking at it right now, and it doesn't have the Cannot Crit flag.
Equipped it to test, got critical hits.
If we're talking weird weapon stats, the Slut Rays (normal, Advanced and Heavy), Bimbolium Emitter, Royal Shard Bow and Goovolver all have Crit Bonuses, but an actual Critical doesn't actually do double Lust damage. At least, as far as I can tell. Heavy Slut Ray also has Bonus Hit Rate, but can't be fired more than once/turn. Unless you have Rapid Fire, in which case, you can get 4 shots/turn.