You raise a good reason not to cancel your subscription — not to hurt the Post’s news coverage.
But given, as you write, that the underlying reason for Bezos to coddle up to Trump is to help Amazon’s business, our logical reaction is a large scale boycott of Amazon. If Bezos is using his wealth, which is derived from Amazon, to undermine independent institutions like the Post, we should not give him any more money!
(I also strongly recommend reading Fulfillment by Alec MacGillis, which documents the devastation Amazon has caused to many parts of America.)