As far as the political fallout is concerned, this makes the PM look guilty of either weakness and inability to do the right thing, or bullish delight in cocking a snook at society by supporting his Health Secretary, and neither of those are a good image for him moving forward.
He should have sacked Hancock instantly, and distanced himself even faster.
By trying to support Hancock, the PM appears to tacitly condone his appalling behaviour and is 'regarding the matter as closed' is either stunningly naive, or again willfully arrogant, and again neither are a good look.
The fact is, Hancock is just as gone whether he resigns or is sacked, the only difference is, what happens to those who are still around, with people asking tall questions about seriously misplaced support.