I find this discussion still very relevant and would also like to request its implementation. @chris clearly explains its use (and qualitative difference in implementation from the other thread mentioned).
When the Alfred launcher is activated, that search window gains focus and should be able to present TouchBar buttons.
These could easily just be a list of buttons matching Alfred's list suggestions (in title and icon), and their action corresponding to activating those suggestions (like the hotkeys Command+2, Command+3, etc. but saving a keystroke).
The idea is not overly complicated, the implementation would not necessarily be either and it would nicely integrated with the MacBook's ability.
Alfred is after all about using your computer to the fullest potential, adding where the OS has not; this seems a perfect opportunity.
I hope other users and developers also provide their vision on this feature here!