KK strange preflop best line?

this was was a bit perplexing.

Villain is a 46/6/3.4, for him to limp utg+1 and then cold 4bet like this, and especially a min4bet - what do you put his range on ? AA or junk? I don't think I've ever seen someone do this with a hand like JJ or QQ.

As I was oop, I thought for a little and decided the best line was to just push to rep AK from my end. What do you do here? The problem is I'm folding out junk this way, and if he's making some strange move I might be better flatting and CR shoving the flop?

$1/$2 No Limit Holdem
6 players
Converted at weaktight.com

Stacks:
UTG browerkid ($392.00)
UTG+1 NEJER ($296.65)
CO GiVeMeTheCake ($200.65)
BTN Kiss Kiss Bang ($236.30)
SB Hero ($250.35)
BB Lord Smoot ($153.95)

Pre-flop: ($3, 6 players) Hero is SB
1 fold, NEJER calls $2, 1 fold, Kiss Kiss Bang raises to $8, Hero raises to $28, 1 fold, NEJER raises to $48

Final Pot: $86

Just get the money in. This guy is so bad that he's calling with almost everything. My guess is that he has AA sometimes and other pocket pairs a lot.

o Pump Fist
o Don't fold