They might consider it a lie if you represented it as a password, and arrest you for it.
They would deny you entry if you did that.
YMMV. I refused a month ago and sat in secondary for 3 hours, but they eventually let me in. On ESTA.
You you could be charged with lying and/or destroying evidence and who knows what else. Definitely don't do that. Worse thing to do is lie or attempt to deceive an agent.
you could require your machine to demand a username as well as password and give them details to a 'clean' user to whoever asks.