Well, no.

The argument of this case is exactly that what they did is not legal because they didn't inform people upfront before the sale

It seemingly (IANAL, but that's my understanding from what I've read so far) is absolutelly legal to sell a device which can be disabled by the manufacturer under certain conditions if the prospective buyer is informed upfront of that "feature" (and depending on the Legal jurisdiction "informed upfront" might mean large bold lettering in all promotional material).

It's also legal if something stops working because it requires some kind of input it doesn't have power (i.e. it's legal if the ICE car you bought won't work if you don't put the right kind of fuel in it).

However selling something as having certain characteristics and then it turns out it hasn't can be considered a Bait & Switch, which is illegal (a form of Fraud) in most places. (Note that this is the direction the plaintiff is comming from: not that it's illegal for the AiO to work like that but that it's illegal for it to be sold without notifying potential buyers upfront of that restriction).

With the legal complexity that comes from the devices working as a one and that scanner not being disabled, just not working when other parts of the device are missing a required input, you need that a judge actually looks into into (rather than issuing a summary judgment) to determine if it falls within the boundaries of legality or not.