It's exactly those hands which take a huge lump out of your EV when you are playing hands like 66. It's one of the reasons that I would consider it to be a poor hand in this situation. The BB is getting 5:1 on his action and seems to be a reasonable player. There are a lot of hands he might play here.
If he plays any two broadway cards, any pair or any suited ace, he drops your equity down to ~36%.
You've still got an overlay, but is it enough?