I’ve been doing WHM for years, and it has been life changing, but I agree with everything he wrote here.

WHM basically teaches you to stop the stress and anxiety process by creating a controlled amount of additional stress, either by cold or low oxygen for a short period of time, and then learning the skill of calming your body down on purpose. Long term this helps eliminate stress and anxiety, but I agree it is dangerous if you are, e.g. already on the verge of a panic attack.

The calming part is also in his courses, and he also teaches calming breath techniques. It’s important to take his actual course and not just do the breathing exercise by itself.

What if the "countermeasures" described here (1-2 breathing, voo-hum, yoga nidra, meditation) have their own risks?

I think the takeaway here should be that all the woo-woo aside, the ability of the body and mind to manipulate itself into a state of stress and anxiety is surprisingly powerful. Anyone getting into these techniques for the doubtful and unproven supposed benefits should proceed with extreme caution.

I suspect this method gave me tinnitus. Be careful.