Your friend's reaction is typical and really why I don't waste my time in trying to help JW's to see that Watchtower is a cult.
I almost never use the word "cult" by itself because it even provokes arguments among ex-JW's. I personally think that all variations of religion start as cults.
CULT: A relatively small group of people having religious beliefs or practices regarded by others as strange or sinister.
Once it gets big, a group ceases being a cult, according to that.
The common definition used today of a cult focuses on the "strange" or "sinister" part. JW's cannot see the sinister part and all religions are strange. They even use that strangeness to recruit- "They all got the Bible wrong except for us."
So I use the full term "Dangerous Mind-Control Cult" to describe Watchtower. That takes the emphasis right where it needs to be, on the dangerous mind-control. Even there, I don't bother saying that to JW's who aren't ready to hear it. But just saying they are a "high-control" group almost sounds like flattery. I can even hear a reply: "Well, maybe we need high control to survive Satan's world."
It isn't their strange beliefs we are combatting. Hell, we have strange beliefs among us. It's the removal of members' ability to think for themselves we combat.