I don't think it's PII. If you had someone's movements, you could go and spy on them, find out who they were (i.e. their PII) and then link that back and say "I now know this identified person's movements". I don't think the movements themselves are PII.

Things that aren't PII aren't "convenient" definitions. Doesn't mean everything that isn't PII is fine to share. It's like saying a kidnapping isn't a murder. That's not a convenient definition of murder; it's just a different thing. We shouldn't start talking like witch hunters as soon as we encounter a situation that we haven't memorised a reasonable response to. We should be able to respond reasonably to new situations.