In this case I do not think there was much choice, since there were only 3 adults. Leaving 8 scouts with 1 adult may have created more serious issues if those remaining had an on-site emergency.

From what has been reported, (in my humble opinion) the scouts and the leaders did an outstanding job. They stopped, regrouped (mentally), made a plan, executed the plan and made adjustments when and where necessary. The leaders kept their heads and provided the support required for the situation they encountered.

Pete