It's a lie of omission, which you could reasonably interpret as a trick to get people to upgrade.
In general, the mobile phone industry has done a pretty good job encouraging their userbase to forget that their batteries are replaceable, so I don't think that most users would consider that as a remediation step off the top of their head.
I think it's plain that the best solution would be informing the user of the problem and letting them choose between behaviors (or, you know, replace the battery), but between slow usage and random shutdowns, I would personally choose the former.
I wonder if there have been any studies on how many users, once the toggle had been added, switched it from the (default) throttling behavior to the shutdown behavior? I'd be curious to see if I'm in the minority there.
No I actually think then the average person would assume it's a battery issue, or at least be able to google it. I'm not saying that this is actually better behavior (I would also choose slow mode over random shutoff mode), but it doesn't obfuscate the fact that the phone has a faulty battery.
The reason I suspect that Apple did this maliciously is that "service battery" notifications are pretty standard behavior (including on their own laptops). It just seems like an intentional omission.
I got an email well before the throttling "scandal" broke out telling me my battery could be replaced for free. It was, 16,000KMs away from home, for free.
What was it Apple lied about?