So, either the Illinois law considers all photos containing faces "biometric identifiers"
It doesn't. The Illinois law they're using to sue considers face geometry scans a "biometric identifier", but it specifically excludes photographs as biometric identifiers.
The plaintiffs are claiming that the defendants digitally "scanned" the facial geometry from the photos, which exposes an ambiguity in the law and a Federal judge basically said he wasn't going to resolve ambiguities within the state's statute and left the issue in the hands of the state courts.
In the end, the suit is likely to fail, at least on the privacy issue. If it doesn't, it could make simply recognising someone in a photo a criminal act. While an involuntary basic human ability, it requires one to visually "scan" the photo and match it up to a mental database of "scanned" faces which the plaintiff's claim the law makes illegal. Of course, there's been far worse legal decisions so who knows? A positive outcome for the plaintiffs would certainly make many lawyers very, very happy.
"The Avis WIZARD decides if you get to drive a car. Your head won't touch the pillow of a Sheraton unless their computer says it's okay." -- Arthur Miller