The idea of forking libinput, vs. simply generating ~$95-150k p/annum for the guy behind libinput to go full-time, is a silly one. He was the same guy behind synaptics, and understands all of this far better than the OP.
That's not a bad idea, though that Peter is already full time employed on behalf of working on this plus other kernel projects. Perhaps seeing the enthusiasm for his project may increase his interest in working on it more. He's been a great help to me in emails thus far.
My interpretation was that the fork is to be a temporary one, with the results of this endeavour to be merged back in when the time is right. This allows them to make mistakes and drastic changes without regard for the release cycle or backward-compatibility promises of libinput, and if everything is successful then they can bundle up the results into a mergable form and get it into libinput.
I feel that this logic is faulty. The reason being if the libinput author hasn't already done this over the past near decade Mac has been trashing competition with their touchpad, it's more likely that they don't know how (or don't care about) implementing that support.
The reason for this is they've presumably implemented plenty of other stuff without being paid to. There's no information given so far to suggest otherwise.
Absolutely no insult to that author though. They are entitled to choose to work on whatever they care about.
Let's get him some bounties! :)