I’m sure I’ve been on a flight where the demo has been done twice, with the crew moving to a different part of the aircraft. I want to say it was a 4 class Club Suites 77W where the crew stood at 1A in first was obstructed by cabin divider so did a whole separate briefing for the small CW cabin forward of D2L.

Personally, I’d write a letter / send an email so that this is in a log somewhere. If there is an incident it would also potentially be disclosable and ultimately safety is everyone’s responsibility and h&s processes / risk assessments aren’t infallible. If you don’t report it, nothing can be done, if you do report it, the company can choose how to respond, especially if they get lots of reports. Maybe a SCCM could ask the tallest crew member to go to that demo position!