I go with the Mechaber
I don’t.
It is not a stretch to say that without cleaning ones teeth it is a vadai, that meat is be stuck inside.
For six hours, every single time? It is a stretch.
you have Rashi, who holds that the shuman stays in the mouth and gives flavor for 6 hours
It’s still not always/vadai. Besides, following Rashi and the Rambam lechumra is not the ikkar hadin either. The Tur’s lashon is ??? ????? ?????? ??? ?????.
the general population (re:not everyone) accepted the halacha of the Rambam and the Rashi
You have no basis for that, and I believe it is incorrect. The minhag is in accordance with what the Rambam held lehalacha, but it is a minhag, not the ikkar hadin as the Rambam himself held; as I explained the Rema.