Doesn't really say much. GP gets games like Wo Long, so it can be done. They apparently asked for a price higher than MS was willing to pay I guess? He doesn't really explain.
I don't typically expect a ton of third party AAA games on GP. It's usually going to be first party, AA, indies, and a couple notable third party games per year (Scarlet Nexus, Avengers, Guardians of the Galaxy, Wo Long, etc). The bulk of the service isn't third party games like Callisto Protocol. I wasn't expecting it on GP at all.