We can't take the term "exploit" so literally when it comes to gaming. This issue is very much on the fence, but many here use the term in much too literal of a fashion. In gaming, that's not all that an exploit is.
I don't know why people get so offended or up in arms over this. Frontier have said flipping boards isn't something they intended, but they obviously don't label it an exploit or it'd be a punishable offense. It's certainly not an exploit in the same vein as old Robigo or the G5 for price of G1 engineering fiasco.
It's like saying animation canceling in ESO is an exploit. (A method of increasing abilities cast/second) The devs didn't intend it, but they haven't found a satisfactory fix for it since day-one so the game is more or less balanced around it, sadly. It has become a part of the game at this point. They still investigate the possibility of squashing it one day, just as I hope Frontier want to fix Board Flipping, but it's in for now and we just have to buckle in wait.
You know, in the end it's just...I'm sorry to say it, but it's not productive to be complaining that others flip boards. I flip boards too, but the real problem is that it isn't fixed. That's what all our complaints should be. But no, everyone points to others' credit balances first, THEN ask for a fix. Should be the other way around.