If you supply drugs (or facilities) to be used in an abortion, you are part of a chain of actions that ends with the intentional taking of a life. Same with assisted suicide.
But even the magnitude cutoff is arbitrary. At which point is the result "bad enough" that ethical reservations start to apply?
If you bake a cake for a gay couple, you are part of a chain of actions that sort of, kind of, indirectly might offend your sensibilities.
Those two outcomes are vastly dissimilar - equating them because they are both "doing things you object to as a matter of conscience" is too reductionist by half.