I was a GI, but wasn't infantry...I was Cavalry. Lots of tankers, artillerymen, mechanics, PAC clerks, cooks, MPs, truck drivers, ADA missileers, etc. that are all GIs, but aren't Infantry.
Whoever told you that needs his/her/it's ignorant a** kicked.
Scouts Out! Cavalry Ho!
If you ain’t Cav, you ain’t sh**! And troopers, not soldiers, but stll GI’s. B 2/17