Without seeing the tune I'd have to say if there is nothing wrong with any engine sensors then the tuner set the PCM table for when engine goes into closed loop with high temp values.

Common of cheaper tune when they do not want to fully tune is they set closed loop temp high thus sensors are ignored.
They could have forced the PCM into the old speed density mode so MAF is ignored thus so are the front O2 sensors.

If a sensor fails on startup then PCM would revert to SD mode.