No, I'm sorry, but this is not pragmatic or reasonable.
It's not remotely clear that this is a 'violation of the constitution' and given that it's implemented in so many other areas and states, there's no way a cop can reasonably make this claim.
That's a lawyers job, not a cops job.
Can you imagine every cop on the beat trying to split hairs in all these situations?
There are tons of little things that law enforcement do that could be feasibly challenged in court.
This issue could feasibly go to the Supreme Court - so how could a cop be responsible for knowing up from down on this law?
It's not like the cops boss said 'shoot that guy who looks funny' wherein the cop would have a reasonable requirement to 'not commit a crime or do something unconstitutional'.
We're talking about traffic tickets.
In court, the cop answered the question as best he could and his honestly basically outlined the oddity of the law.
Let the courts decide the constitutionality of it all.
There's a well-known standard of "probable cause". A cop is supposed to know what that standard is, it's part of their job description, and it pertains directly to what they do every day.
When a cop is asked to claim that there's probable cause when said standard isn't met, it's clearly and plainly an illegal order, because they're asked to lie. Doing so under penalty of perjury is doubly illegal. He doesn't need to be a constitutional lawyer to determine that this is illegal and cannot be obeyed.
This is exactly the same as doing a search without warrant, or arresting someone without reading them their Miranda rights, or lying under oath (something that the cop had also admitted to doing, by the way).
That this also happens to be unconstitutional is coincidental. It suffices for the cop to know it's illegal, and act accordingly.
And if they do know their orders are illegal, but follow them anyway, they should be held responsible accordingly.