Some smaller airports are pretty sleepy. There's no control tower at his home airport (Corona Municipal Airport) and it doesn't look like there's an FBO there. There's probably generally no one at the airport unless someone is there to take their plane up. Even if there is someone there running out to the ramp every time they hear a plane startup would get tedious very quickly.

There are even just 'airfields' here, if that's even the proper name. They're just well maintained grass fields with a place to tie up a plane and refueling.

Maybe that's too far in a rural area for this conversation though.

Why would we need to tie up a plane? Would they fly away otherwise?

Yes, they can!

Strong gusts can move an unsecured plane, and damage its wings, tail, or propellars. Properly securing the plane prevents it from rocking or tilting in a manner that might do those things.

They literally mention FlightAware and him using it in the article.

He knows the website exists, does he know he can put an alert on for his plane?