I like that they mentioned that they did this for cheap, but did not seem to care that they were calling ~1000 random people. And they plan to do this regularly.
If you want to get mad about people spamming this phone number with fake calls, you're about 40 years too late. The numbers are already spammed to hell; there's hardly any harm in one more call every 6 months to document the phenomenon.
I was never mad. I read the article as basically "I called a thousand random people. Don't worry, it didn't inconvenience me to do so." A statement I find silly.
I think the article gives pretty understandable reasoning of why the owners these <400 numbers, of which <100 were actually in service and accepting calls, are ones that are expecting to get called just to see what's on the number. As it explains these numbers are not something given to a random grandma who is going to be bothered by the wasted minute on their phone plan.
I would still find one prank phone call every six months annoying. I get that it's probably a small drop in what the poor people that unintentionally have that number deal with, but it's silly to think the readers would worry about the cost to the caller not the stranger called.
My number is unremarkable and I still get a half dozen spam/scam calls a day. An extra one in six months would go unnoticed. If you're not in my contact list, you go straight to voicemail.
We get that half dozen as what we call 'ghost calls' -- the caller has hung up by the time the outgoing message ends. It might have something to do with my putting SIT tones at the beginning of that outgoing message. If their autodialer doesn't drop the call entirely, it triggers their message, so we hear it start partway through; either way, we know not to pick up.