He is just a super fan, most artists have one, like Gaga and that one fan whose name I can't remember right now but y'all get what I'm saying.
The fan clearly has a crush on him though.
I'm going to pull a little detective here and say that if you look at this tweet, it feels disconnected and him losing his **** over it clearly shows that he adores Shawn, something common in fans but if they were really close then he wouldn't make a big deal out of it, besides, most of their photos together wouldn't be before Shawn's concert or randomly bumping with him.