Interesting fact I found out last week of Oct20201. CLU had been planned as one of the main characters of the comic that turned into the TRON 2.0 The ghost in the machine.
The script had been written and proposed to Disney, and they were supposed to do the pre-tron comic. But Disney chnaged their mind mid way and wanted them to tie it into the end of the Tron 2.0 game.
so tldr: CLU would have 'met' Tron before the movie (aka stalked) and Tron started a revolt against the mcp while CLU used the distraction to go through securered areas an stuff.