You can't judge his behaviour without knowing his intent, and the culture of the late 80s and early internet.

Everyone hacked. When the internet was connected to Sydney University early 90s, all the students were grabbing Stanfords /etc/passwd files and peeking at the open X displays of people in Sweden. Etc. All for fun / curiosity.

You can be sure that even rtm's Dad did similar, perhaps confined to his lab / peers.