I can't imagine that it could ever happen. Primaries are State sanctioned elections of party affiliated candidates. Ballot access restrictions in almost every State prevent third parties from participating in the primary process.
I’m not remotely suggesting anyone vote for the Libertarian party. That’s a non-starter. I’m suggesting that others not dismiss libertarian-leaning Republicans.
As a shorthand, capital-L “Libertarian” normally means the Libertarian party. Whereas libertarian refers more broadly to all those who want who to reduce governments’ control of our lives.