Maybe marines get touchy, but as a ex-servicemember, who cares what people wear?
Are they wearing it to be a poser? I guess maybe you'd think that. Do people actually think only Veterans wear "Grunt Style"? If I wear a Ralph Lauren shirt, am I posing as a Polo player?
Maybe they bought the shirt to support the Army Veteran's business, or received as gift.
Unless it's a drag costume or furry

or something, then I could see people caring.
We got Combat Veterans doing drag or furry as well, who cares.
A 8 year old boy wears a SWAT shirt, you think a SWAT member would swat the kid?