What lesson exactly? That if the ideal candidate isn’t run, a subset of liberals will pick the worse of two options?

All that does is teach the conservatives that if they can convince you that the democrat candidate fails you enough on a single issue, they effectively have your vote. Regardless of the conservative candidate’s stance on that issue.

You have made the choice to make the problem you care about profoundly worse because there wasn’t a way to make it completely better. Have fun watching that play out as you intended I guess.