"Pausing must be a core mechanic" - but can slowing down time be considered a pause?
Some games when pausing games are not completley stopping game world, just slowing drastically(like 70 or 80%), so when you use pause to slow down time and it's core for the gameplay, then It is considered as pause.
And also, how you interpret it is up to you I guess, the important thing is to just follow the limitation.