I was under the impression that NIL allows a player to make money advertising various products using his name and likeness
Seems to me to be a two way street in that the company involved gives up their money in return for this player so why shouldnt there be a guarantee from the player to participate in all games to secure the money commitment
but I dont pretend to be a legal expert so maybe it is only a one way street
Because NIL is not a pay-for-play deal, it's a pay-for-advertising deal. And in some states, the NIL laws explicitly prohibit any clauses that would be considered pay-for-play, which is precisely what you are suggesting.
In its true form, NIL is nothing more than allowing NCAA college athletes to benefit from their name, image, and likeness, in the exact same way that all other college students have been able to do, since the dawn of time. The NCAA forbade it, and I understand their reasoning, but it was never legal, and the states have decided to enact specific mandates that overrule anything the NCAA previously had in place. So NIL's true intent, is simply to grant explicitly to college student athletes, the rights they already had, but that the NCAA illegally prohibited.
Many NIL deals-- in fact the most lucrative NIL deals-- aren't tied to any university whatsoever. They're simply brands, that want a popular athlete to advertise for them. Ewers' big deals are all negotiated separately and would be granted to him no matter what school he chose. The deals he signed when he went to Ohio State, are still in place with him at Texas, because he negotiated those deals directly with the companies that want to use him to help advertise their brands, and those companies don't care where he goes to school, as long as he remains a high profile public character.