I seriously doubt that Google would have signed on to Matter if it didn't provide an abundance of ways to gossip about you.
Google supporting the standard is irrelevant so long as Home Assistant does. More devices in the eco system at the beginning is a plus for the health of the standard, just don't buy one of their listening devices
Google might be pretty much okay only capturing the 99.99% of people who don't think about privacy much, and want the convenience of Google Home and centralized data. Giving a slight nod to the 0.01% might even lead to a decrease in bad PR.