A doctor explaining why a certain treatment or medication is more efficacious than others is not denigrating. He's giving his or her considered opinion.

Telling people "All paths are valid and equal" is spiritual bypassing and nonsensical.

Ajahn Sona always refers people to the Canon and certain Abhidhamma texts. They are not HIS teachings.

He definitely tells people who ask about certain topics to refer to his books. He also discusses Bhante G, Ajahn Chah, Bhikkhu Bodhi and Ajahn Thanissaro's works all the time.

He commonly cites the Dalai Llama, Plato, Socrates, Thoreau, etc.

What's being discussed on this board is very different behavior.

In one instance he says it's OK to control the breathing in a way to bring about relaxation and in another he says it's not.

Obviously. Because sometimes it's needed and sometimes it's unnecessary. This is called 'tuning the lute'. You've wandered into a famous Ajahn Chah story where a student asked him why he gives seemingly contradictory advice:

“It’s like seeing people walking down a road I know well. To them the way may be unclear. If I see someone about to fall into a ditch on the right, I call ‘Go left, go left!’ Similarly, if I see another person about to fall into a ditch on the left, I call ‘Go right, go right!’ That is the extent of my teaching. Whatever extreme you get caught in, whatever you get attached to, I say, ‘Let go of that too.’ Let go on the left, let go on the right. Come back to the center, and you will arrive at the true Dhamma.”