Yes, it is very disrespectful and intolerant of other peoples' beliefs.
Even though I'm atheist, if a patient asked me to pray with them, I'll listen to them as they pray, and hold their hand if they want me to do so. Just because I don't share someone else's belief system, doesn't mean that I can't respect their belief system and the practices that go along with it. I haven't encountered a JW who made that request of me, which I suppose is due to their belief that I'm not worthy of praying with them or on their behalf, I think I'd feel really weird though if they did.
JWs would feel that they are being disrespected if someone behaved that way at one of their services; they would call it intolerance. I guess the difference is in the cult mentality that perceives only their belief system as being correct and every other belief system as being utterly wrong.