I would take it to mean that the horse is still in a place in his training that he requires the support of a rider with the skill to reassure him. (What self-help book was that? I’m OK, you’re ok? "Lol) There’s a horse that I don’t ride but sometimes handle on the ground that I joke that if he spoke English, the entire conversation would consist of him asking if I’m OK, if he’s OK, and if everyone else at the barn is OK. Because it sure looks like their coukd be sharks in that puddle next to the mounting block and he feels responsible for warning us, thank you very much!
By contrast, there was an UL event horse around here that stepped down into a new career as the mount of a tentative adult amateur in her 50’s. This had been like a CCI*** or CCI**** horse. And he was happily tooling around the puddlejumpers at local horse trials - he knew his audience well and took great care of her. This horse had reached a level of confidence and competence that he could not only execute his job with minimal rider input, he could also hand-hold a rider.
It’s certainly a training thing. But also a mental/native personality thing, IMO. Some horses will never get there.