Maybe they were blowing it up to stop 5G rays from spontaneously generating viruses, in which case if they didn't really know what they were doing beyond a surface level it wouldn't come as a huge surprise.

It's not any rando that can get access to the levels of explosive necessary to do this in the domestic US, it's actually quite hard.

If you don't need it to be predictable or timely or anything than filling the interior of anything large with propane/natural gas can be enough to create a boom like this. It's essentially just replacing quality with quantity

Also on a vaguely related note getting annual statistics for meth lab explosions is surprisingly hard

Doesn't fit.

Either that, or they understood exactly what they were doing and simply needed to shut down 911 services for a while - perhaps so they could commit some sort of crime without the authorities being able to be summoned or coordinate.

Although someone choosing to bomb a place means I wouldn’t be surprised if they weren’t thinking everything through...

The announcement to move away shows a lot of planning.