You consider doing the job you are paid for to be sabotage? He was contracted for 7.5 hours, he was paid for that and nothing more. In what universe does the company deserve more than what they pay for?
I hope we both know that there are more ways than one to do your contracted job well. I might choose plan B that does the task but needs replaced intwo months, than job A which takes longer to implement but might be efficient over the long run. In this case, would you dock my pay?
I'd expect you to present both and I'd make the decision since it deals with costs. If I expected you to make decisions like that that directly affect the businesses future expenses, you'd be making a lot more money and wouldn't be contracted for 7.5 hours.
Then pretty soon you will be micromanaging me, essentially doubling your cost. At some point you have to trust me with some decisions if you want to be able to operate somewhat efficiently.
If you want someone to show independence and to work more than what they are contracted to, then don't tell them they are just an employee and nothing more, pay them what they are worth, and don't renege on earlier verbal promises.