It's actually a technical problem - Valve is running 1 bit computers that, due to binary origins, can only represent 2 states. They'd love to release hl3, but that would require coming up with the whole new architecture - at least doubling up to 2 bit cpu. Imagine the headache of adapting all the toolchain to build the game!
See, that's a common mistake - MPFR library is a C library for multiple-precision floating-point computations with correct rounding. Valve is, unfortunately, still stuck to integers. Their floating point appears to be functioning correctly as they've managed to avoid kernel panic releasing hl2e{1,2} - you can look at that as floats 2.1 and 2.2.