Anyone going to Communion with the sin of abortion on them is asking for it. The Bishops show her no mercy by letting her receive. There will be lots of folks answering for this one day.
The idea is that they should suffer the consequences sooner rather than later, that they be made an example to those like them.
Faux excommunications to her would be like tying a string of tin cans to the tail of a bad dog. Everywhere she went, the rattle of her hypocrisy would follow.