If he wants to be bought out for more, then you sit him on the bench/suspend him.
But I'm not as anti-Camby as some are. He's in his last years and was really expecting to be part of a Knicks team that challenged for a championship. Allowing his disappointment to be seen publicly is a faux pas, but that disappointment wasn't directly AT toronto, but AT not being part of a contender. He will suck it up, and either mend fences with toronto, or agree to a buy out/trade on Ujiri's terms.