It’s almost certainly all made up.
It isn’t a nice thing to mock, not because I care what Putin thinks, but because I care about the impact on the people, in the UK, who fall and/or soil themselves. It’s common, and people often feel terribly ashamed.
We spend quite a lot of time in hospital reassuring people that it is a bodily function, nothing to be ashamed of, and national headlines mocking somebody else for soiling themselves are really cruel, IMO, because of the message it sends.
It’s hitting the wrong target. Putin won’t care what the Sun says about a fake story. An elderly person who has fallen and soiled themselves WILL feel worse about themselves reading those mocking articles.