I doubt that he's the mole, because the MOLE came up with that idea with the hand drill — and it was a great idea!
Why bother with that gadget if your goal is to personally get to that task yourself? If that’s your objective, there’s no point playing around with the drill, because you can sabotage the task in a million other ways without it.
Let’s imagine we have that task — seeing just the tools, the watermelons, etc., I would’ve definitely started by cutting open at least a few watermelons. That’s totally understandable! Even without the mole there
The mole’s goal would be to DELAY reaching the people with the watermelons, so they’d have as much time as possible to mess around, destroy the watermelons, speculate, and wonder if there’s something inside them. That’s why I’m almost certain the mole would’ve preferred to be on the elephant team and try his best to delay getting to the watermelons.