Oh it counts, sadly you will get a bunch or jokers who will say no because they are heavily invested in books they mistakenly think are the first appearance. Nice work on finding this one!
I said somewhere in the Is Spider-man Superior thread that Marvel Previews 2 actually contains the first Superior Spidey. No one acknowledged my post at the time.
I remember very distinctly picking it up and flipping through it. It came out one week before DD21 even if you count DD21 to contain Superior's first appearance. Even if you discount Marvel Previews 2, which was free, I think it's really Avenging Spidey 15.1 that's the first app.
Anyway, a year from now Superior will be inferior and the title will be canceled.