Whilst he was a bit of an arse in how he put the point across, it is incredibly important stating the intended future use of the images and any implied licence because, as a commercial entity is involved, it is very different to the competitions usually held here.
For example by posting an image to the competition thread, you are granting an implied licence for TP to publish that image within that thread ONLY.
If
MPB (or TP) make any use of the image, other than 'hotlinking' to it on there, then they are creating an infringing copy for which they could be taken to court.
You cannot assume anything in regards to copyright - it has to be laid out in black and white for everyone to understand.
Because without that happening, you have no usage rights at all - and that would be pretty much useless for a commercial entity
who are likely to want some traction from sponsoring the competition, even if it is 'just' on their own social media.
So, yeah, it is actually a pretty big thing.