The programmer inadvertently used a vendor-specific feature. This is the key difference. Nobody writes perfect, standards-compliant code all the time, so the compiler needs to tell you when you are doing this.
Right, but it's a trivial fix, in this case at least. I'm happy as long as standard code works in their compiler. Considering how much trouble MS are having with getting their compiler standard-conformant, I'd rather they work on the more important features.