Howard Stern took a shit in a diaper on air(or pretended to). I can and will mock him for this. Not because he wore a diaper, but because he wore a diaper when not necessary and made a spectacle of himself.
Donald Trump mocks people for their age even if they're still able to ride a bike, when he won't or can't walk a couple hundred feet with a bunch of other political leaders, while he's incontinent and his opponent isn't. I can and will mock him for wearing a diaper, not because it's ableist, but because he's a hypocrite and deserves to be called out for it.
I will mock his followers for wearing diapers, again, not because I'm ableist, but because they're using medical devices when they don't need to, both making a spectacle of themselves and supporting a hypocrite who makes fun of disabled people. They are deserving of criticism not only for what and who they support, but also how they show that support.