It is hard to be confident that you are looking at the actual weather they are flying in. I couldn't find any time stamped archived weather regarding convection, winds aloft, or turbulence sigmets.
I'm viewing it as a long repo flight, into significant headwind.
The descent to 15,000 may have been to check winds at lower altitude. It looks like they increased ground speed from 210kts up to 245ish with the descent. But probably fuel flow goes from 450 up to 650. More efficient at 28,000.
Can any of you Jetprop guys talk about the fuel system and the risk of flameout due to...
underfueling,
misconfiguring fuel selectors or pumps,
If you were distracted, how easy is it to overlook a low fuel indication/warning?