the ustaz have a point though. you need to look at the whole speech.

in his words, the is a hadith where muhammad shows cleaning up the mosque is an honourable thing to do.

so from this hadith, the ulamas conjectured that cleaning up other worship house is akin to honouring the other religion. hence it reaches "syirik" (polytheism).

furthermore, there is no pressing necessity to clean up other worship house.

this is what i think. but the ustaz maybe forgot this polemic started in the midst and context of flood disaster. so maybe other muftis can detail and outline the fatwa needed.