Android Chrome not having extensions is just a build option toggle. It doesn't have extensions because Google doesn't want it to, not for technical reasons.
Yea, I very much doubt they would ever put a browser extension on this. It's funny, I feel as though reading some Google dev's response on reddit about why mobile chrome didn't have extensions was my inflection point when I started to realize they were becoming evil.
It'd be really weird if extensions got enabled/disabled based on whether the USB cable is plugged into a monitor or not.
I expect the eventual production version of this will have extensions if and only if the normal Android Chrome has extensions at that time.