I’ve only been in a couple of Muslim countries. Malaysia is fairly relaxed and, for the tourist, the people are mostly friendly but, when we went, the shadow of PM Mahathir Mohamad was intimidating. You had the feeling that things could get nasty very quickly.
In contrast, communist countries were disheartening due to the enforced poverty, but much less tension. The average person in the street was friendly and often curious/envious of capitalist culture. Being able to speak the language may have made the difference (Laos, Northern Burma - Tai Yai).
Religious fervor may be inherently more threatening.
I would tend to agree....I would have been at least curious to visit the former Eastern bloc during the Cold War, sure I knew I'd be watched at all times, but at least I would have felt safe.