Earlier quoted context omitted.
interesting: given that it may at any time hit that line of GPL'd code, your claim is that the rest of the code can be MIT licensed? i am not a lawyer but that sure seems like a borderline case at best.
The author can licence their source code however they want. The GPL doesn’t relicense other code either, it’s that the GPL asks you to additionally follow its terms for the whole resulting compiled distribution
https://www.gnu.org/licenses/gpl-faq.html#IfLibraryIsGPL
The problem for the author in this case is that a) writing their code against a GPL'd library constitutes creating a derivative work, and b) putting it on GitHub is distribution.