I'm not actually sure we can say with any certainty that the original plan was to stay outside, and that this was unexpectedly changed.
This information appears to have come from the same source that has mentioned panic, getting lost and other information that is not substantiated, and doesn't fit with what we know of the divers previous history and skill set.
Until we hear from a direct source such as one of the dive team or surface support what the plan was, and that it was changed, I think it would be safest to treat this as speculation, albeit resulting from hearsay from someone who may have go this from one of the dive team.
I know this information came from the police spokesperson, but in my experience (32 years police including time as a senior investigating officer) it is uncommon for the spokesperson, or even the senior officer rolled out to talk to the press to have actually spoken to witnesses themselves.
The comments attributed to Gallegos, about Shane going in against the plan, does not fit with what Young told the Tribune that they were looking for tunnels and both went through a restriction and in to a chamber, no mention there of any change of plan.
It is at least second hand and of dubious accuracy.
P.