1. A bunch of greedy corporate doctors (Who I can only assume collectively constitute "Big Jaw") suppressing the lone heroic voice of medical genius because money and evil and so forth.
Because the Medical Industry has never done anything except in the best interests of its patients.
2. Youtube.
Because if someone put a conference talk they did on youtube, it's automatically discredited.
3. "Even if it doesn't work, at least it's not expensive"
Compared to what some people have paid for dental work? What kind of moron wouldn't at least try it, if for nothing else as a supplement to orthodontic work?
4. A clear implication that if it doesn't make sense to you, there must be something wrong with you.
Yes, if something doesn't make sense to you, there's a zero percent chance that it's your misunderstanding and not the material itself that is at issue.
5. Irrelevant but touching details as an invitation to engage in special pleading.
Not sure what you mean by special pleading, but he can't in good conscious charge people money for a study he's doing where the patient is doing all the work. What an entire industry might be guilty of, he surely is guilty of?
6. Things that read a lot like relevant scientific articles but are either not peer-reviewed or not specifically addressing whether the thing works. Sloppy science, in other words.
His dad was actually cited as the epitome of sloppy science by his detractors, yeah. They actually destroyed his career, as they are angling to do the same to his son. But if you maintain #1 as "just another conspiracy" then yes, I guess you can go with that. For something that does no harm, and costs no money, it seems odd that the British Orthodontics Society and other institutions came after him so aggressively. Multiple times even, when he was cleared to continue practicing previously. You could make the argument that such advice prevents people from seeking legitimate treatment is doing harm, and that's a reason to revoke his license. Then again, when you can give a possible option to people who may not be able to afford thousands of dollars of corrective work, it's hard to call that harmful when, if it doesn't work, they'll probably seek standard treatment anyways.
Basic advice like "chew more gum to increase your jaw muscles for corrective action" is apparently radical enough to get your license pulled in Britain, so free-thinking and flexible are their institutional bodies.
7. No actual evidence.
His actual talk.I didn't find any peer reviewed research in a quick search, but I don't have access to any periodicals where they may have been published. And even he admits more research and time is needed to see how his theories play out.
I'm not saying I believe it whole heartedly. But for the way they destroyed his father's career in Orthodontics and are coming after his now, it made me stop and think. And though I don't have a 3,400 study meta analysis to back up this supposition, the idea that your mouth works the way your rest of your body does when it comes to posture doesn't seem like frickin' rocket science, black magic or deep medicine conspiracy.