I disagree with assertions that 1000-2000 feet is not low for aerobatics. That is not enough height to recover should he/she make an error of judgement .
As a general rule, you should be above 4000 feet, over unoccupied land.
What your chappie is doing is :
(a) Irresponsible
(b) dangerous to himself and potentially to others
(c) probably beyond his capabilities - his actions would seem to tell me this.
(d) certainly detrimental to the GA cause
In my humble (PPL of 30+ yrs exp) the man is an ar*e .....