Is this cheating? Or just efficient grinding?

Wanted to run this by the community before I did anything. I found everything I need to customize a map on my MVM server to allow a wave of 1,000 very weak robots. Using this setup, the amount of time needed to get grind out "Metal Massacre" would drop from months to several hours. Would this fall under "efficient grinding" or "bannable cheating?"

I don't see it being any worse than achievement maps, and as far as I know, those aren't considered cheating. Valve made it easy for players to create their own custom waves too.

EDIT: I mean, it's even considered ok to do so on AStats, and we both know how anal they can be about "cheating".

So long as you still need to play the actual game to earn the achievements, it is unlikely to be punished.

Please be aware that unlocking large clusters simultaneously, or within short time frames, may lead to a user reporting you. For that reason, I would recommend that you make some kind of record of what exactly was used since we will need to investigate - my team can only work on factual information so I think all parties would prefer to avoid a "my word vs time stamps" argument.