while his statements are not incorrect, you can never claim 100% truth on this subject (harnesses/cage/seats in street cars). Nobody has done enough testing to confirm a lot of the "truths" out there.
Ideally you'll need to read up A LOT on the subject from multiple sources and not just take one person or company's word on the subject, then form your own opinion. Ultimately there are great solutions for the track, and for the street, but never one good for both. There is some risk calculations that you'll have to decide what you're comfortable with on your particular setup.
To go ahead and start the fire, I am absolutely against full roll cages in street driven cars. Back-halfs or roll bars you can get away with, but anything that has a bar beside your head WILL hurt you in a wreck without a helmet on.
I would much rather see people drive with fixed back seats and 3-pts (which I'll likely do in the FD this year) on the street and track as I belive that the theory of "the roof caving my head in" is a risk I'm willing to take.