Aye, I'm guessing that they're primarily making sure it's not been disturbed by some idiot in one of the units deciding that they needed to put a screw into it.Checking that hazardous building materials aren't a threat to health sounds like a pretty reasonable way to spend the council's money.
It's something that I suspect will be part of making sure the building is safe, at the same sort of level as making sure the fire alarms work etc and may be a requirement for the insurance (if the units are council owned).
Given it's described as being under sinks, it's not unreasonable to do a periodic check as it sounds like it's in an area that sees plenty of use and may be prone to damage from normal use, or clumsy maintenance.