Count of mutators is not affected for result.
Ex. I have mutation with 100% chance (when I tested Jaded bee restriction) and big Alveary without mutators. Chance 100%. If I placed Mutator block in Alveary, chance changed to 15% (15.000001 see in console).

But if mutation chance is 2%, placed Mutator with Ender Eye changed chance to 8%.

https://github.com/ForestryMC/Binnie/blob/master-MC1.11.2/src/main/java/binnie/extrabees/alveary/AlvearyLogicMutator.java#L49

That's funny! :)

Should this be considered a bug? Looks like an attempt to make a balance.

I think that was added to prevent the player from making an aveary out of (almost) only mutators to get the mutation chance up to a ridiculous level

Then it does not need fix.