Just thinking out loud::
I think A-J is likely as well...but is so why would he go spastic on the river...If he thinks he is on top why not bet another $5...something you and ginger are essentially obligated to call and then pray for a raise.
If he was on a flush draw I would think he would simply raise big (while he has enough $ to make a real impact) on the turn repping the ace (good scare card w/ a J out there) and take it down right there.
In the end - I am thinking he had J-J from the start and either got overly excited and bet you out at the river or intentionally did that to make it look like a half-hearted steal on the end to encourage a call into his boat.

Were you able to find out what he had - I am really curious now....tough call either way, probably a good laydown (I would have been really...really tempted to call just to see what he was capable of) In the end I think you saved yourself $12