10ms is an upper bound. Games typically don't do a lot of allocations during gameplay, so it's unlikely that Go's GC would be an issue for most gaming applications.
And, as I mention whenever this comes up, Minecraft is written in Java and suffers from huge GC pauses, yet it's one of the most successful games of the last decade.
And yet the GC pauses are noticable and annoying. It's not game-breaking because Minecraft is just that good, but I doubt it'd work well for other games.
I brought up Minecraft as proof that gamers are willing to tolerate the occasional bit of lag. And, honestly, I haven't played an AAA game that doesn't lag out and drop frames from time to time.
To return to the topic at hand: 60fps is 16ms per frame. The proposed GC would achieve sub-10ms pauses. So, worst case you might drop the odd frame. To assume that Go is unsuitable for games because of garbage collection is to ignore reality.
And, as I mention whenever this comes up, Minecraft is written in Java and suffers from huge GC pauses, yet it's one of the most successful games of the last decade.