Shameful.
Google has many choices: don't implement clear-text geolocation presence, don't implement RCS, speak up in the standards committee, communicate the implication to Google users, etc. Google chose to silently use a dark pattern to enable 24/7 location snooping.
Shameful.
"Share with your friends" means "Share with your friends, and we'll snoop/aggregate everything that's ever shared by anyone using our platform in perpetuity and use it to subvert your will, haha 'private communication' is so XX century".
RCS is yet another excuse to implement this dark pattern, with explicit provisions to include unencrypted 24/7 geolocation information in it. Google just rehauled their Android messaging strategy around RCS. They deserve to be called out on it.
PS. You claimed "The feature being discussed here is literally the ability to manually press a button to send your location to your contact." Until you take that back as factually false [it's continuously sending, not gated by a button press per send], we're done here.
Frankly there is no way that Google's RCS app streams your location to any endpoint without an explicit opt in in the app. I'll eat my hat if I'm wrong.