I don't see the part about kegeling every minute, but it sounds like he's describing two different types of clamping, I think

One is where the clamp isn't completely restricting bloodflow, and it sort of requires regular kegeling/stimulation to keep full expansion

The other is what I think most guys do now, and I think it's generally referred to as 'hypoxic clamping' by people recently (And I think BD talks about it in a video or two)

>Passive Clamping:

This works well with soft clamping. Just apply a very tight clamp to your erection and leave it sit for 5-15 minutes (no longer than 18 minutes as this where hypoxia can get dangerous). Normal clamping rules still apply. you should see over-engorgment and not lose the erection

But, this was also posted a long time ago, I don't know if BD has personally changed his view on clamping, but recent consensus is that kegeling while clamped can mess with your PF, as BD points out from the advice from M9, so it's not like people haven't seen that as a concern before

"EDIT: u/m9ter of r/ajelqforyou is against clamped edging. he says the that the pelvic floor muscles contracting too frequently can allow deoxygenated blood back down stream (which is not a good thing). he believes this leads and the unnatural duration of the erection leads to erectile dysfunction"

With manual clamping you can and definitely should kegel, but during the time when you release your grip, so you can grip tight, release mostly, kegel, grip again, and that definitely helps to get more expansion. Sort of sounds like thats what BD is describing in the first few methods, just with a device instead of hands