Grilling down to the alleged justification of overlooking (even if not facilitating with an open parking lot) congregants driving to shul on Shabbos by saying it keeps them Jewishly engaged, that defense is absurd and unacceptable as the rabbi is clearly encouraging actively violating Shabbos and Torah law.
Encouraging trashing of Jewish Law to supposedly keep them “engaged” is completely unjustified and kneged halacha.
And is exactly what the Conservative movement was condemned for when they first started permitting driving to their “synagogues” on Shabbos.