A person needs to find one consistent halakhic hermeneutic (“mehalech”) and stick with it.
Case in point- If I follow the Gemara/Rambam/ShA and eat something made on hezkat halavi with meat (Hullin 111), then I should be consistent and also not use our eruvin. Or, on the converse, if a person believes that they can clap on Shabbos, there should be no reason why they shouldn’t eat vegetarian cheese that isn’t gevinat yisrael, since the same principle matirs both of these things (the approach of Tosafot is that changing circumstances can override Talmudic gezerot; Tosafot allow clapping on shabbos in contradiction to 2 gemaras in Betzah 30b and 36b, and in Avodah Zarah 35b, s.v. chada, Tosafot allow vegetarian cheese made by nochrim; Rabbenu Tam says that the gezera was due to the use of nevelot, and therefore, that wouldn’t be a concern in certain cases).
There is a gemara in Horayos which condemns one who is maikil all the time.