I think that calling pre-flop is good, for two reasons. first of all, the one you mentioned being: there is a guy with 20bb, who could potentially shove, so ‘ slow-playing’ JJ here is good for this reason. Secondly, you said UTG2 is a maniac, generally speaking you would want the maniac to ‘do his thing’, which generally is to bet and punt it off. 

On the flop, it is a standard call, QQ8 is a safe board, with two queens out there, there aren’t many queens left in his range and a maniac will always c-bet here. On the turn however, I think you should start to proceed with a lot of caution. The board is QQ82 and he shows strength in his betting. 

Even maniac’s have ranges so let’s take a look, he double bet and is increasing his sizing so strength. AA/KK/QQ/1010/99/88/77, AQ/KQ/QJ/Q10, J10 (bluffing with gutshot straight is possible), you didn’t mention flush draws so let’s assume it was a rainbow, if not: all flushdraws could be double barrel bluffs. but against all these hands, AA-QQ you’re basically dead, 88’s have FH, all queens you’re practically dead, so we’re only doing well against J10 (which we block) or double barrel flush draw bluffs.

Personally, I think shoving is the worst option possible, simply for the fact, that we are NEVER getting called by worse and allowing him to fold his bluffs. Personally it comes down to this: you ‘can’ call, but you are in for a massive bet on the river, so if a blank comes, are you going to call again? unlikely… but there are two options letting it go on the turn and wait for a better spot, or call turn and hero call the river as well(which is extremely marginal, or downright punting)