That's just a simple example to show how to read distance from the sensor, without any radio interaction.
There are other samples
in the same repository that illustrate various ways and examples if how you might use the SonarMote. For instance I use it without the radio as a parking aid.
Read
this page as well for other examples.
The sump pump node uses
this sketch, but there is no OTA for that. I think once you tweak the sketch there is no real need for OTA which is more complex.
I have not changes my sump pump SonarMote sketch for years and it just works without a hitch.