Absolutely support this!
Honestly, despite all of his good character, thoughts, intentions, viewing of sharpteeth's nature, etc, love to see how Littlefoot expresses how he wants not to only protect newfound valley from some sharpteeth who are about to enter the valley, but also to, ahem, literally get rid of one sharptooth who brought him a huge pain and who can continue to do it again. And I don't think it's OOC or "pure corruption" or something! Not here, since he's still 5 years old child who ended in hostile environment and tough situation for children of his age! He can act like this or say something rude in the most tense moments, like when he told to not say stupid stories about Sharptooth, when he fought Cera or when he screamed and left the rest of the gang when they prefered to go other way.
So, in my vision, I would like to see mix of both script's and movie's versions, when Littlefoot explains why they need to stop Sharptooth now by themselves, and then angrily adds a sentence about killing him for good once and for all.
And lol, I even wanted to write his thoughts in fics, what he actually thought in that scene. Then how he panicked and thought he has just led his friends to their death because of his plan to make personal revenge in the most part of his plan, when Sharptooth jumped at the cliff with stone that rejected to move, and now they're all will die because of him. And then, after talking with his grandparents, remembering Rooter's words, and selfthinking, he changes, and this change was a reason why he looked at newborn Chomper in that new way.