Your example is unambiguously plural. It's not a good illustration of "they" creating confusion.
It's truly not a problem. I could contrive a reason to talk about a couple (they plural) and a nonbinary person (they singular) and end up with sentences where you don't know which I'm referring to, but the exact same issue happens if I'm telling a story about two "he" or "she" subjects. And it's solved in the same way.
Can we clarify what "not much different" means? I'm not mad at this guy for calling people names...