[BluffTHIS!]

In a cash game in this situation with the stack sizes involved and considering he is a maniac, I almost always only call his initial raise, since there is not even 1 nut flush draw possible and the 2 side cards are relatively low. If you could raise enough to set youself or him in then I would do it. But since he is a maniac and will most likely bet any flop, you now have to call that last 1K yourself if you reraise not knowing whether he hit it or not. And if you only reraise as you did to 300 and then call, he still most likely knows what you hold if you are seen as a tight player. Typical hands that I have seen a maniac reraise with after having raised initially indeed include a better KK but also something like AKJ9ds.

By only smoothcalling, you give yourself a chance to trap him with a good flop, which will not only include an ace of course but a low board pair with no flush draw possible or a hand with your 2 sidecards. And since the other player involved had only 100 in the pot already as opposed to the circumstance when he is between the maniac and you, the amount of his dead money being left is not enough of an issue to me to tip the balance into reraising.

All AAxx hands are not created equal, and in any case even the best AA hand such as AAJTds is not much more than a 2-1 favorite in omaha, unlike the situation in holdem where aces are a 4.5-1 favorite over another pair. I would only reraise holding double suited aces or single suited aces contain two higher adjacent cards.

It is frustrating playing plo against a maniac who is always raising and betting, thus putting the pressure on you to make a big hand or a big draw on the flop, and in plo I believe maniacs have found their perfect game. Nonetheless, I try to see the flop and thus evaluate how big my edge is then before putting a lot more money in, when I am against a maniac who will call any amount of money to see the flop and then will chase with any low percentage draw or bottom pair only. Plus by escalating the pot even though holding the best hand then, you are making more nearly correct his betting/calling allin on the flop by virtue of the odds being laid by the pot to his remaining stack.

One thing is nearly for sure, if you reraise and he does not set you both in, then it will be awfully hard to get away from even the ugliest flop for your hand like QJ9.