I went to a few Clash concerts in the 1980s and probably should have expected the same since they were as left wing as any group could be but they pretty much played their music and said a few things which could easily be ignored. I suspect they knew their audience of North American punk rock fans would only take so much before they would start rebelling against too much yakking.
Imagine that! I suspect Roger Waters was not in the least bit concerned, in that respect. Because, after all, HE knows better than anyone else about these things.
Pfft.