You can only grant something you have the rights to, so basically, they are asking you to do something you can't.
I don't have the rights of my client's product.
I want to see how it plays in court.
I don't have the rights of my client's product.
I want to see how it plays in court.
If you sign a contract to license something to Adobe that you don't have the rights to, you're now at fault.
Either get a good liability insurance, or avoid using Adobe.
Or get the client to direct you to use Adobe even with this clause.
Easiest solution is to get the client and Adobe to agree to what rights each of them get.
You're correct that the two conflict, but I think the courts would have a problem with you for using a product that breaches the employment contract you signed rather than rule that Adobe is at fault here.
Realistically, businesses will either shrug and be fine with you using Adobe stuff, or they'll find someone else (who still uses Photoshop, but doesn't know or warn about this stuff). I doubt the person hiring artists knows or cares about this stuff until an actual leak takes place.
Poison the well?