I think that with 12bb A5o its not a good hand to defend on BB because has a bad playability post flop and you will be commited if you call a cbet or raise. If you think villian has a wide range above 35% 3bet shove is the best option in my opinion. If you are not sure its ok to fold A5o and wait for a better spot

Call is fine from BB as you get a great price. As played check jam flop.
You can also 3bet jam this preflop as it looks like he opens too wide

I would suggest that both options in the BB are fine.

Personally, I would prefer the 3B shove over his OR. Because he is aggro he will fold a high percentage of his OPR.

If he is extremely passive post flop(doesn't cbet enough/folds to donk bets/folds to a bet on turn after CB) it is a good opportunity to defend and donk bet range preferential flops/or checkraise all in on range preferential flops when you back gutshots/backdoors.

Would like to hear your thoughts.

yeah, vs a loose aggro player is better just shoving the Ax hands

I've been in the situation a few times recently and I think the most important questions are what was the average stack size and how many of the remaining players had stacks shorter than you? More often than not, I find I make the money by waiting for a better hand and not acting and letting 8 others try and improve their stacks and get knocked out.

of course the strategy can change if the average bb's is 6 or 50, or if we are near the bubble. But in general, we can't avoid EV+ spots