Oh dear, not this one again.
If the POH does not say it's a limit, then it's not a limit. The Cessna 152 and (older) 172 manuals explicitly state that it is not a limit.
What is limiting, though, if we're talking about a school, is the school's FOB. If the FOB says the POH number is to be treated as a limit (or gives any other limit), then it becomes a limit.
FFF
-----------