That's not a major factor in this, afaik.

A) you need the new timezone definition available and pushed everywhere regardless. It doesn't matter what zone the RTC uses.

B) For future events, you need a way to manage what happens when the time zone they're scheduled in changes OR when they change to a new time zone. Microsoft has been terrible at this part on every time zone change I've been aware of (it's hard, but it's not this hard, and the Canadian change was published with sufficient notice, and time zone changes happen for recurring events, this is not a new requirement). But there's no connection to the time zone of the RTC here either.

If you have issues with poor behavior specifically around transitions, that could be related... Repeatedly moving forward or backward for DST is something where keeping the RTC in UTC would help.