OK...my son is 7 and also occasionally sits this way.
I notice it. And have wondered the same thing as you. Will he be teased?
My hubby does not sit this way...however I have known many men who have, including: my own Father, hubby's brother, my Uncle Bubba, my BIL (and he is big dude, tattoos, plays in a band, bald head) I admit, sometimes it makes me giggle to catch my BIL sitting like this. I guess I am guilty of thinking it's funny!
Lots of men in my family sit this way. Usually they are all just relaxing and enjoying some conversation...that's usually what all of these men are doing while sitting this way, even my 7 yr. old.....
I think it's just comfortable for some of them.
It is what it is.
I have yet to point it out to my son...probably never will.
FYI: All these men in my family have a similar "vibe" to them...they are mellow, intellectual and naturally inquisitive, funny and all around cool!
comfortable for them.