Good to hear you were okay. Squalls like that can be very scary for sure. We have spots that has pretty crazy. wind...Wind changing direction, going off shore, sometimes being super squally so I am not entirely unfamiliar with what you are talking about although your situation sounds pretty extreme...I think the it is scary when you jump, and the wind changes direction on you while in the air...especially since there about a foot of water then reef.
Anyhow, I noted you saying that the other riders were on 5 line kites and therefore just released their kite and therefore were safe.
I have three points here that I am thinking of.
1. makes me think about what would happen only a few years ago when kites had a way smaller wind range. C-kites were crazy in winds like that...but you could still release them.
2. Flat kites bow / SLE should be releasable like that too. I've ready about kites doing crazy loops upon release. I don't think that is acceptable.
3. If not released flat(ter) kites has bigger wind range, but needs a little technique riding in winds like that. I found two ways to ride out nuclear squalls. One is to put the kite in the water on its side, which I don't really like..the second is to ride it like you did, but always remember to keep some tension on the backlines. Of course different kites does react different to different conditions and I have my latest experience on the shockwaves and helix which seem to handle it quite well.
I also basically think that in many case looking at wind charts in squalls will many times only ba a weak indication as small local circumstances are wildly different in terms of strength and behavior, and most charts are averages over a time period. Maybe you were caught in something that was a lot lighter only a few hundred feet away..even in the same squall. There is no way to know though.
I posted a post a few weeks ago about how to ride through crazy squalls, (where the squall hit so hard it ripped the bar out of my hands)...and think there were some good suggestions there.
I really think that we absolutely have to think through what we are going to do in a situation like that BEFORE it happens. What about if you had not been as experienced as you are? It probably could have gone way worse than it actually did.
Anyhow good to hear it went well...