If he's smart, that replacement HomePod will have a Sonos nameplate.
JK, maybe a replacement one would work better, but my own experience is that the HomePod has wifi issues. But Siri issues could also point to an Apple server problem, and there was a thread last week I think, about Siri flaking out kind of across the board. I saw some iTunes issues at the same time, so it could well have been a problem on Apple's end.