No, we're on your back for making really silly arguments. If the Epsicopalian Eucharist can somehow magically and/or miraculously prevent some weak Christian from becoming a Mormon, then why can't it prevent a weak Christian from becoming an Episcopalian?
The Episcopalian Church is in open apostasy and yet they supposedly have an apostolically authorized Eucharist every day and twice on Sunday. If by their "fruits" ye shall know them, then clearly with all the "fruits" running the Episcopalian Church we can know they are apostates. The Eucharist didn't help them.
The fact of the matter is that you proposed a rather silly premise that can easily be refuted. The Eucharist does not save a person and obviously it does not prevent a person from falling into apostasy. You might want to leave well enough alone.
To me, the old saying “Familiarity breeds contempt” tends to take over in many folks.