My reading of the discussion at https://forums.swift.org/t/swift-concurrency-roadmap/41611: the Google Swift team members expressed hope for a bit more community involvement in the Swift language planning, and Apple folks very politely told them to shove it where the sun don't shine.

My guess: Google concluded that investing in a language developed behind closed doors of another company is a bad deal.

I don't blame Apple, it may be a good business decision for them, and of course it is completely within their rights.