I mean, if were going to speculate, the most likely thing is probably mode confusion or simply being unaware of which mode was in use. If the A/P didn't capture MDA for whatever reason (someone with experience in this airplane can comment, but perhaps alt-capture or whatever it is called in this particular avionics package wasn't armed or available) and the airplane was tracking the localizer and simply descended right into the ground.
Or maybe it did capture, but they didn't push the power up at MDA and they stalled it. Or maybe, they were getting ice and didn't use enough power, or maybe they lost control during the transition to visual, the list goes on and on - we don't know yet. My money is on the autopilot not capturing the altitude, or it being set up wrong.
Frankly, I'm fine with speculation - if I auger in, speculate about everything, if it gets you thinking about safety and possible failure modes, then maybe I didn't make a crater in vain. Still, if you're going to speculate, at least speculate on what is likely. I mean, while it's likely that Execuflight is the typical FL charter company, it's silly to say that the reason they crashed is simply because "sketchy company." If anything, that's intellectually dishonest about what causes accidents. Sketchy company is just one layer of "swiss-cheese" or just one "link in the chain" on the way to the scene of the accident. Just my $1.05