I have a lot of experience with flat bottom boats such as that one, although I've never run one aground at full speed so I am very much speculating. In any case, from the picture itself it's unclear whether it ran ashore or was dragged, but I am confident that it is obvious to anyone on the ground there. But from the picture I can see factors that could support either scenario.
Ran aground:
-There may in fact be marks from the motor that are not visible in the picture. That sand looks pretty hard-packed.
-The motor more than likely WOULD end up in a position similar to that if the boat ran aground. They are not necessarily locked into the "down" position, a lot of the time you can just lift the motor to where it locks in the "up" position.
-BIG problem a.) that motor would most likely still be running and cause a huge racket for quite a while, unless it had an automatic shutoff (which would be most likely worn by Matthew and engaged were he to fall out of the boat--also in my experience these are rarely used)
-BIG problem b.) if that boat ran aground at a high speed with Oliver in it, there is a high likelihood he would be thrown out the front of the boat and, at minimum, seriously injured.
Pulled ashore:
-The problem with pulling the boat ashore to that place is, those boats are super heavy and in general it's pointless to do so. A large, seemingly healthy adult man such as Matthew probably COULD do it, but why? If you're making a brief stop on shore, you pull the boat just enough out of the water (~90% of the way or so) so it's stable. Makes your life way easier.
-Also the motor appears to be kind of half-up half-down, which, if you were pulling the boat ashore under normal circumstances, you definitely wouldn't drag the motor bc a.) potential damage and b.) increased drag to an already difficult task.
-The only reason I can see that you WOULD do that is to avoid leaving footprints--drag the boat from the front, pull the boat over the prints, get up on the roots by that tree where it doesn't appear to be sandy anymore, and make your way out of there.
Without better visuals/more info in general, I would lean slightly toward the boat being pulled ashore, but I'm not feeling strongly about it either way.
Any way you slice it, this is incredibly strange.
