Can barely figure out where to start with WR's comment.
US carriers don't "have" to operate extensive domestic networks, and in fact they regularly cut unprofitable routes very quickly.
US domestic flying is some of the most profitable flying in the world, due to the fortress hubs and limited competition through mergers on most routes not touching NYC, LAX, or SFO. When they actually have to compete internationally, they have a hard time making money.
Statutory corporate tax rates are not a good barometer. Effective corporate tax rates are in the single digits.
Essentially all the US majors have used the US bankruptcy process to shed obligations to their workforce. Gary Leff has done a decent job listing the many ways the US government has subsidized US airlines.
Unfortunately, the most likely scenario is probably that WR gets his wish for even fewer taxes and less regulation. What he may be surprised by is the much higher fares and even worse service and product that the US majors will inflict on US domestic flyers, and internationally if they manage to stifle competition there too.