As far as I understand, PtP and PtD only differ by name. How can the network tell what a file is? Maybe it is a compressed library or an encrypted document - it cannot know for sure and even if it tried to detect a file type, you could create, say, an application encoded as an image.
However, if there is an indiscriminate fee on PUTs/GETs paid to the maidsafe foundation, then it is a bit different (I don’t think this is considered PtD though). It would only be to the foundation’s benefit to make people perform unwanted PUTs/GETs, but I suspect the network would fork as soon as such nonsense was attempted. Therefore, I doubt the incentive would ever materialise.
(BTW, I am not debating the pros/cons of the maidsafe foundation being paid, just observing that it would be unlikely to be gamed)