Because the primitives are converted/swayed. SOP is to use nonlethals if there's a chance they can "save" the person. Same reason they hadn't killed Lash.
That was less "left" and more "oh shit we didn't plan for this let's lock everything down and reposition". Which worked, I'll note. They just didn't realize, at the time, the stuff with the quinjet.leaving Hive unsecured in cargo bay
I'm not sure any of the team are doctor doctors. People like Doctor Radcliffe use the term, but I'm pretty sure it's PhD-Doctor, not MD-Doctor. Jemma's a biochemist. Radcliffe's specialization isn't mentioned (I think), but he's a scientist working for an agrochemical company; little reason to think HE'S an MD rather than a biochemist.letting Mack do the cauterization while there are doctors present.