That's not completely true. It would be trivial to find people to work on Python 3 support if they were paid. It's just finding the volunteers that's hard.

They say pretty clearly that they're not working on it because the donations for that goal are exhausted and that the money they have was donated to be focused on other parts; that they would be interested to make Python 3 support better if the donations were there.

Myself as an hpc user of python (this pretty much sounds like an oxymoron at this point) in deep learning, I would be much more interested in having solid numpy and c extensions support (tensorflow / theano maybe?) than python 3, and I feel that many people feel the same way. The only reason to use PyPy is performance; making it very compatible with the other main source of performance gains in python (c/c++/fortran extensions) feels like a strong priority/ a no brainer