Though as I understand, spacex doesn’t actually use GFOLD, but a related (and secret!) development

Not to accuse spaceX of anything, but I've witnessed companies sell 'hyper-localised weather" where they take public weather information and average the nearest two datapoints to you.

So I always take 'secret' 'proprietary' data and algorythms with a bit of salt, as almost every time I dug into them, it was all spin on previous public stuff.

In this case, SpaceX is actually landing those Falcon boosters pretty reliably now. So maybe their secret proprietary stuff isn't as advanced as they make it out to be, but whatever they're doing it does seem effective.

The two have apparently co-authored the relevant papers. So perhaps both of them "learned GFOLD at JPL" in the same sense.