To me it seems like these researchers are saying the switch is confusing and complicated. That is not to say that Apple secretly collect data after lying to their users.
The problem with Siri, first example, is more about Apple’s (characteristic) terminology garbage. Siri’s voice control has nothing to do with Siri’s search suggestion, yet they marketed both as Siri. Actually, you can turn them both off, but since the voice control is just called Siri, they confused their users.
That’s different from "collecting data even when supposedly disabled.
(Tbf, even if they were better termed, my mom would still manage to confuse herself… mo matter what Apple do, the average user won’t be able to turn off anything.)
That said, there’s no point trying to convince someone on the internet anyway, and so I don’t really know why I wrote this comment.