I don't really understand this sentiment. Management joining or not should have 0 effect on standup. They should only be there to hear what folks are working on and or also to give their own updates.
Management being present really does change the dynamic of pretty much any meeting. I watch as junior members of the team either clam up or start show boating. There is even a correlation between camera off and management being present. IMO developers have their best discussions when there is nobody there to impress.