There's nothing stopping this developer from taking the requirements of the project and developing a solution from the ground-up in their language of choice ove

There's nothing stopping this developer from taking the requirements of the project and developing a solution from the ground-up in their language of choice over the course of a couple weeks. Yes there is: if you can't get it done in 1.5 months having already spent 1.5 months working on it, you're not going to get >3 months of start-over work done in a couple weeks. Never mind the boss freaking out at the thought of you abandoning 1.5 months of work, knowing the remaining time isn't enough left to complete it (yes, he knows) much less start over from scratch using completely different tools. If you had that kind of alleged ambition and talent you wouldn't be in this mess to start with.