It looks like you answered your own question. Yes it can be used. Should it.....probably not.
Ok, but I wanted to know if anyone else has used Window Perf for a windshield banner?
It was Orajet 3675 and has a very low tack, maybe I should have sealed the lower front edge somehow?
(Pretty sure) legally you can put anything above the AS1 line.
All perf has a lower tack adhesive than regular vinyl, no matter the brand. That, combined with its thickness, conspire to make it unsuitable for putting on the windshield. Not only will wind peel it off, the wipers will too. If you have to put something printed on the top of a windshield, use vinyl with normal adhesive. You don't need perf because you shouldn't be putting it anywhere in the driver's field of view.