Ladislaus posits the formal/material analysis is the wrong approach altogether.
That's the one issue I have, the other being that the crime being participated in is not REMOTE and PAST, but rather PRESENT and ONGOING. This is the major contribution from the NO bishops here, even though they did not properly articulate it.
In taking the vaccine, we are not merely participating in an isolated act of abortion that happened 60 years ago. We're participating in the ongoing and present crime of using fetal cell tissue in vaccines. We're participating in the entire abortion industry. We are participating in something that's been wrongly and falsely legalized by our society and are therefore condoning this "legalization".
And the other implied point here is that, even to justify a "remote material" participation, there must be proportionately grave reason. These bishops assert that abortion is so grave that the proportionately grave reason to justify even a remote material participation doesn't exist.