"experienced" isn't an exact word, and really its a gradient.
However, I would generally describe someone with 100 dives as experienced. Not necessarily an expert, but no longer a beginner, i.e, experienced.
If a diver hasn't mastered the basics of diving by 100 dives (assuming continual diving), its probably not experience that is holding them back.
And many an experienced diver makes mistakes -- sometimes BIG mistakes.
Lots of inaccuracies and poor wording in reports, but I wouldn't call this one out, especially as the reporter qualified their wording with a number of dives.