I take buses infrequently and almost always with a buggy, which theoretically folds.
I've never had to move or fold, although I have had to wait for the next bus a few times when the space was already in use.
But if a wheelchair user wanted to board the bus, I'd get off, because I am not an arsehole that space is no longer available to me and getting off would be less hassle for me than folding, not least because it wouldn't wake the baby...
(a) there are big signs on the bus saying the space is for buggies only when no wheelchair needs to be there, and reminding passengers of the wheelchair user's legal entitlement to that space. I can't recall the exact wording but it is firm and unambiguous. It's really good.
(b) there is nowhere you could possibly stow a folded buggy even if you wanted to as the seats are so close together and there is no luggage rack or compartment at all.
I can see that the legal judgement accurately reflects the relevant legislation, but I am disappointed by the reporting of it 
One has to wonder why so many people are arseholes.