Personally I think the solution to this is obvious and apparently so do many others here. Daily standups within a mostly stable and well-functioning team are almost always redundant at best and actively disruptive at worst. So don't have daily standups. Instead work on a culture where people communicate freely whenever they need to and you bring people together for larger and longer meetings when (and only when) you have a specific reason for that.
I'm always a bit amused when Product Owners are suprised that there's nothing to clarify at a daily since the team is constantly transparent towards each other about blockers etc.
True. Whenever I've done freelance/consultancy stuff in the past my rule has been that if a client invites feedback then I'll test the water once. If they're receptive I'll elaborate. Otherwise I'll usually drop any process-related feedback and fit in as well as I reasonably can with everyone else since IME that is normally the most effective way to work in that kind of environment. It's always a bit disappointing if you can see a client making obvious mistakes and you know how to fix them but sometimes it happens and if they're not interested in changing then ultimately that's their decision and their responsibility.