Cyrus had been watching near them after getting in.
He didn't know how things came to this point but he knew if he stepped in now and protect Heather then it will look like he was not listening to his mother at all.
She had already spread the rumors of Heather not listening to her.
People who have herd of it will think the same goes for him if he stood beside Heather.
And those who heard of it will and sees this situation will think that the rumor wasn't entirely true. Heather was simply having a mind of her own but both she and Amanda does not have a common ground.
These kinds of thoughts were what Derick didn't have causing him to take side and causing the balance to break.
This time, it will look like they are bullying Heather, telling her to just listen to her mother-in-law without voicing out her own thoughts.
Since they already broke the balance, Cyrus could conveniently step in.
"She is still MY wife, sir Cooper."
