The cause could be that inside the block there were already the /* */ comments, and editor did not have single keystroke option to add // at the beginning of each selected line.
Ok. So I have another theory. In place of false there was previously some ugly condition and he wanted get rid of the things that were done on this condition with minimal necessary effort hoping that someone in the future with more time (maybe even himself) will clean that up since doing cleanup in such case is not hard thing to do.
