IMO using automatic comments, as proposed, is not a solution, but I would hate to write a comment to someone who is suspended. I normally do not check the profile before writing.
I suggest highlighting (lowlighting?) the user name of an suspended account, when it is displayed as author of questions, answers and comments; e.g. using strikethrough or an yellow foreground/background.
I think there are't be that many suspended accounts, I'm not sure if it is worth the effort of doing so, but I think it would be useful.