Porting Java to Xeon Phi would be a good CS project. As to if the end product of the project would be desirable for others to use... that would be up to the implementation and to the particular type of applications you run with Java.
An alternative to running Java inside the Xeon Phi is to use offload mode. A likely good starting route would be to use JNA (Java Native Architecture) for Java/C++ or Java/Fortran interoperability.
I suppose some people have tinkered with java native (e.g. gnu java compiler) on Intel(r) Xeon Phi(tm) but there is little to brag about if it can't deliver better performance than it does on a modern laptop.