You're right.
Until something is stated, I'd do what I said.
Cop are allowed to keep people longer than 10 minutes because of combat, and transporting people to hq can be time consuming so people are not allowed to log if restrained for over 10 minutes by a cop unless you have been ignored for 10 minutes.
And I think at some point in time people took that rule into consideration for civilians as well.
A lot of people follow it as that, so I would still not log after 10 minutes for you're own sake.
Also that could be way out of date. Not 100% sure though.