safeik derabbanan and rov

Earlier this week I posted the Bais haLevi’s distinction between the rule of safeik derabbanan l’kula and the rule of halacha k’divrei hameikel by dinei derabbanan. The sugya in Eiruvin 46a debates whether we can pasken l'kula like a da’as yachid, a single isolated opinion against a majority, in dinei derabbanan, or we only pasken l'kula when it is an argument of one opinion against one. I think it is obvious that a rov can be used to decide a safeik derabbanan, so why would Rava think that a majority opinion rov, acharei rabim l’hatos, does not apply? Based on the Bais haLevi, I would suggest that this is another point of distinction between the rule of safeik l’hakeil, which can be influenced by a rov, and the rule of halacha k’divrei hameikel, which works even against a rov. You could argue that I am conflating two different types of rov and try to distinguish between acharei rabim l'hatos (majority opinion) and a regular rov, but I’ll leave it to the comments to see if anyone wants to take that approach.