whether Baitza 2B (and many other places),Pesochim 74B,
Those are not rayos, as discussed (in fact Beitzo 2b indicates the opposite).
the klal that in sefeikos we go lekuloh (certainly in a miderabbonon)
Now, we’re getting somewhere. That’s a legit rule, but we must be cautious not to apply it where the poskim don’t. Your implication that it might apply to a d’Oraiso as well is ridiculous, though. You must know the rule that “safek d’Oraisa l’chumra”, but you seem to ignore that one. (That one has its exceptions as well.)