That's not really true. The accountants start with what the client gives them and adjusts anything that is material. They have a huge obligation to the end user. Also, any accountant worth their salt should have found these issues way before any allegations arose.
I would speculate they won't sue MYEC directly because MYEC has the easy excuse of 'I didn't know. I'm not an accountant. Our accountants said it was OK, etc etc.'