[][]You can still see their quotes posted by other users [/]

But the quotes are part of another user's post! You want to censor another user's post becuase of an ignored user? Leaving aside the issue that technically it would be difficult to do so. [/]

The quotes are quotes, they belong to the one who wrote them and not the one that copied what the other one wrote. I don't think it is techically difficult to do this. You can attach user ID to every quote before you put it in the database and do the display:none; on it to make it invisible.