The intent is a fact of what actually happened: which appears to be that it was written by an employee within the scope of employment to solve a business problem. Possibly outside of usual working hours, but if it’s by a salaried employee where doing work at home outside of usual working hours is itself a normal if not consistent part of employment, is probably not particularly significant.

That the employer later chose not to make use of it doesn’t change the circumstances of its creation; businesses often choose to not pursue use of exploratory work done by employees in the course of employment, that doesn’t surrender ownership of the work product.

And the version that was further developed within and in response to Uber business needs and actively used at Uber before the function for which it was used was terminated is an even clearer case (insofar as it is a distinct work from the original) of work-product (that it quite likely is also an unlicensed derivative work by Uber of proprietary Box code doesn’t mitigate that, though it puts Uber in the position of potentially being both a beneficiary and victim of IP violations.)