3 of 3 expanded on the summary to give figures who said this, and that the concern was hillul Hashem

Indeed, some say to pray in one's seat, for precisely the concern you mentioned, of Chillul Hashem.

According to this VosIzNeias article, an unnamed Manchester rabbi "told a meeting that it is better to pray in your seat rather than risk a disruption by standing in the aisle", and his motivation was concerned "about the impression made on potential passengers, especially if Jews simply got up and tried to pray in a minyan". Commenters on that article cite other rabbinic figures saying similarly.

According to another VosIzNeias article Rabbi Yehuda Leib Steinman also ruled that it is preferable to say Shemoneh Esrei on a plane sitting down.

This is all rather one-sided, in that I've presented rabbis who agree with your reasoning and conclusion. That is not to say that there might (in theory) be other rabbis who would disagree.