That's all true of course but they do offer shuttle almost everywhere else in these situations. The problem will be lack of buses to charter in that area.
What I hope happens is that HAL arranges for all of the ship excursions to begin at Somaneset. They already had the vehicles booked so I wouldn't think it would be that hard to change the pick up spot. Those with private excursions could also arrange with their tour providers for a Somaneset pick up (probably higher cost). Then it's a matter of finding shuttle arrangements for those not on any type of excursions. Not easy if there are other ships in Stavanger that day.
Not a great situation for sure.