Come on now... Granted it doesn't prove it, but it does support it.
Let's assume for the sake of argument that bacteria were proven to be unable to survive re-entry (I know thats not going to happen - this is a logical point) then that would absolutely refute panspermia. Well this experiment has proved that that's not the case, so the argument for panspermia is strengthened as a significant obstacle has been removed. And in any case, the central point here is that the bacteria would not have that capability if it hadn't been selected for - on that basis this bug has had a fairly traumatic history in one way or another.
Re your equation... It's true in my universe! :)