The fact that he wears a hat, and recent observations of him in red boots, suggest to me that he has a sense of fashion.
The phrasing and construction of this sentence is familiar to me. If you've encountered the sentence on a quiz or such, know that the writers of these assessments often use:
[Singular 3rd person subject] [long parenthetical set off by a pair of commas, but often ending in PLURAL] [present tense third-person SINGULAR verb].
It sounds like a "gotcha" question to me. If someone has gone to all of this trouble to write (or purchase) a test item like this one, you can bet that the answer is going to be corrects. Fact and the single verb suggests couldn't be considered wrong: Fact … suggest … that?