Is there anything that makes you believe they'll sacrifice quality to have universal support?

They did their initial AirPod implementation in a pretty insecure manner because it was securely locked to their hardware and they could trust themselves to not be malicious. If they have to build a feature, plus all the security around it, plus documentation, etc… it makes it much harder to bring to market. They may opt to skip it in favor of something else.

Spite? It's standard practice for corporations to take the ball home when they are forced to play fair.

They won’t, but Apple previously lied similarly against PWAs.