This gatekeeping feels weird. As the sibling commenter points out, both sides of the aisle have used "thin blue line" to refer to themselves. I'm neutral to it, and I voted for Hilary, Biden, and Kamala.

But you could be right if some people in the conversation voted for "defund the police". Those people may be enraged by a single mention of a "thin blue line" and be unable to focus on the technicals.