Not passing judgement or touching the merit of the whole subject but it is a very consistent position of the right in the United States to oppose regulation passed down by unelected officials of the executive branch instead of legislation created and approved by the legislative body through their elected representatives.
It is a similar phenomenon to the one occurring in Europe with its maximum exponent being the Brexit process, also motivated in a lot of ways by the perceived interference in the day to day life of the British by regulations passed down by unelected officials of the European Union instead of legislation created and approved by the local legislative bodies through their elected representatives.
In America, opposing FCC mandating net neutrality through regulation is akin to other similar rejections of "legislation by the executive":
- DEA or Department of Health legislating controlled substances
- FAA legislating personal drones
- FCC legislating TV language and obscenity
- ATF legislating gun ownership, possession and storage
- Treasury Secretary legislating penalties for failure to enroll in government approved healthcare (Obamacare "Tax Penalty")
It is all part of the same phenomenon, people pushing back against what they perceive as a federal overreach in areas that deny people proper representation in contesting the regulations imposed.
Trump got elected on that exact platform by the detractors of such overreach and it is only natural that he is going to follow the desire of his electoral constituency.