Aha , you want to talk about this?
OK,
1) A terminal doesn't even have a CPU. It's a terminal , not a PC. That's why you , as a terminal , can't / won't think.
2) A terminal CAN reject anything from mainframe as long as the protocol is not compatible. Or, I should say, a terminal won't response any command from mainframe side.
3) The virus is not a necessary a "bad" thing. Technically , a computer virus is a process based on a piece of code. No difference than any other regular process. And a terminal won't be infected by any virus, since there is no process running in a terminal. It's not able to run any process. If there is a virus in system, that means your God is infected .
Since you said the BIOS/OS is written in Holy Bible, and obviously you mentioned virus, which means you observed some abnormal behaviors of the system or received illegal commands from mainframe, than , as a terminal , you can do nothing but carry on the command from so called CPU. Just like what you said , you can become "either blank or chaotic".
No matter what, as a observer, who is not even in your system (not a terminal like you, not a printer, not a monitor, not a bus, not ..... totally out side of the mainframe system), I would simply say "Oops", and walk away.
Or, of course, I can choose to stay and see how badly this system will cause, with or without a cup of coffee.