That complicates matters. It'd be difficult enough to tranq each of the guards without setting off the others. Now he's got two extra sets of eyes heading his way.

"Copy."

Better to let them pass and deal with the new rotation first. Follow up on the previous guards with their back's turned. He maneuvers himself into a corner, waiting. Watching to see how this plays out.

"Two guards rotating out, heading towards entryway."

So that's still four for him to take out. Just a little more waiting than he was expecting.