They flew Cat I Approach or divert ! As you know if the wx is bad in TEB it will be bad at a stone throw away too ... that s why most of professionnal operators doing Long Range take the fuel for an alternate at least 200NM around the final destination if the Wx at ETA is marginal at the time of Departure ! but its still possible to operate that kind of flight like the local flying club too...
you are right most of bizjets operators are not CAT II / CAT III, because you have to be trained and checked twice a year when some operators don t even go to the sim once a year.