Delta flight out of SLC almost takes off with O2

I just got back yesterday from a flight to Seattle, it had a stop in Salt lake City before heading back to Dallas, we taxied out to take off and the pilot said something about a Cargo Light so he took us back to the terminal, there we sat for one hour while 2 elderly passengers were booted off the plane, they apparently checked a full size hospital O2 tank in the cargo and the pilot was not comfortable with it in the belly of our plane. Sharp pilot, my question is how did the O2 get on the plane in the first place? Shouldn’t the airlines not allow it to go? So glad we had a smart pilot who became aware of this before we took off. Really scary in a way seems I have heard O2 tanks and flying can be a disaster …

I guess that pilot never flew a business jet. Instead of oxygen generators bizjets have oxyen tanks built in. Having said that there is a difference between carrying one as cargo and one that is certified for flight.