Please make "Training Grounds" bot mode active for all levels

I'm an older gamer, soon 50, and the Training Grounds that has 2 player squads on each side and the rest bots was a perfect fit for me. I am very saddened this game mode deactivates at level 20ish. 

And don't say "play Portal", these modes with bots do not work. People joining them replace bots. 
Also, I saw the devs respond to the amount of bot servers on Portal causing issues maxing out the servers. Having the Training Grounds mode active would help reduce this.