Again, Google autism and depression, or better still talk to someone. You probably know someone with depression or autism. Autism is a spectrum disorder that has many forms.
Here, I've made it easy for you
https://www.autismspectrum.org.au/content/what-autism
From their website:
These behaviours often manifest in an intense and focused interest in a particular subject matter.
Autism does not mean that a person can't function at all.
As for depression, well that doesn't mean one can't function 'normally' either.
So perhaps this person had the equipment and listened to calls. It's not difficult to detect patterns and standard phrases; hold on, that's how I learnt radio calls, but I digress.
Yes, he knew what he was doing, but filter that through the lens of depression and autism and put on your compassionate pants and it might be easier to understand how he did this (assuming he has been found guilty that is).
We are very quick to say 'let's wait for the investigation ' or 'the pilot did a great job of avoiding the school' when it's an aircraft accident, but wait for the investigation into this to establish the facts, no!
Great Mob mentality on show here.