I think the argument for using the line is, there is no reason in the moment not to try everything you can, no matter where you are, and you adjust based on the situation. If you’re in a place that doesn’t respect the rule of law ALL THE TIME, sure, don’t. Is the US(I will assume you’re US-based) that right now? I think your answer to that question == whether you feel the tactic is viable.
But you’re right, we shouldn’t be in this place as a nation, wondering if police are going to be ethical even most of the time.
The main point was that there is a line between being cooperative and being tricked or forced into consent for a search. The best tactic is to appear cooperative but not a pushover. If they are forcing or tricking a search, then you need to show that you are complying but "under protest". And definitely, this is based on how it is now, not where we should be.
But you’re right, we shouldn’t be in this place as a nation, wondering if police are going to be ethical even most of the time.