To be fair to Matt Hancock, it really wouldn't occur to me that hospitals might NOT test covid patients before sending them into care homes, because it is beyond stupid.

Also, as described by Cummings himself, at the beginning they did not realise that it was mostly airborne, and that they over emphasised washing and underestimated distance, so if the care workers were following infection control properly, and if covid was transmitted as they thought at the time, the possibility of it spreading within care homes would have been unlikely.