I'm curious how the idea the that each model is an individual psyker is suddenly a valid interpretation when we already have other Brotherhood of Psyker units that are clearly not (Daemons for instance).
I mean the first sentence says all we need to know about power generation should work:
The entire unit is a single psyker. Not made of individual psykers who roll for different powers, just a single psyker. As such they get 1 power and that's it.A unit with this special rule counts as a Mastery Level 1 Psyker.
Seriously when you have multiple people telling you that your twisting the wording of the rules and reading it wrong, well, you're probably wrong.
EDIT:
Not to mention the asinine levels of book keeping to do something like keeping track of who has what powers and making sure you don't use powers you lose when someone dies or their head pops doesn't really fit with GW's method of rules writing (though Daemons does come close).