howflytrg,
Was the limitation at MAN caused rather by the runway assessment:
'may be slippery when wet'?
This should appear on NOTAM. It's triggered when the minimum friction level drops below 0.5 using a Mu-Meter or 0.55 using a grip tester. It's up to the Operator to request further information from the Authority and promulgate to Aircrew. Until that info was given, restrictions may have had to be put in place.
Same thing happened at Heathrow a while back.