I think we have a bit of a crunch coming.
Brown, White, Pageau, Tierney, Anisimov, are all NHL centers right now imo (Anisimov less so, but he's under contract and will be hard to move).
Norris is going to be ready soon (late this season or next season imo). We could be in a position to draft an NHL ready center in Byfield this Jul.
Lots of people also see it as a decision between Tierney and Pageau, keep one or the other. I can see the argument for either tbh.
I agree that we could hold onto a good NHL center in Tierney, that's certainly not the end of the world. Having said that, I think trading him this year likely maximizes the return we can get for him, so doing so is betting on him not being one of our best three centers in a year or two and going forward.
I think if we want to play it safe, hold on to Tierney, if we want to swing for the fences, we trade him.
To your specific point about some saying we won't need him when we are a contender, while at the same time saying trade him to a contender, how far away are we from being a contender? 3 years? 5 years? Trading him to a contender gives that contender his prime 3 to 5 years, holding on to him might give us the start on his downward trend. I don't see the logical inconsistency there.