I think it is widely understood that how you dress conveys a message (office gear, uniform, party dress, casual etc). And that we, as individuals, pick up on body language even in its most basic form.
This is probably even more apparent to those in the public eye, who know they will be analysed ad nauseam.
So, "I choose to dress like this" is a clear message. EG, H wearing his uniform for the Marines do: I support you, I am one of you.
M's glam red dress last night, to me, said: I'm an equal half of this couple, it might look like a sop to his RM service, but actually it's about the optics and the insta pics.
If that were me, in their situation, I'd have thought: this is his gig, for his people, I'll wear something lovely but relatively discreet and not too flashy, because it's HIS thing.