Trust me, I'm not a lawyer, but parodies, as I understand the law,do get an awful lot of protection under fair use. In this case you have a supporter of Soglin's, the photographer, who took a copyright picture that is suppose to offer a flattering image of the subject. The tee shirt using that image mocks Soglin. It may be 180 degrees from what the photographer had in mind for its use, but this would seem to fit the parody definition.
The bigger and more interesting issue here is how Soglin is seen as a hypocrite because the once young,, party animal hippy is now a crotchety old fart. I give Soglin credit for admitting that the behavior of his youth tends to annoy people of his current age. It's a a shame he hasn't likewise matured out of liberalism entirely.