"A tow-truck driver said that the beheading "just affirms what I thought before. We're not being tough enough. This is something that we've got to do. We should attack our enemies directly and not back off till we succeed." "

This is the "reason" why the US a Republic and this is better than a merely a democratic state. It's not surprising that a tow-truck driver would say this. It would be surprising if this same tow-truck driver after being elected President of the US would say this. It would surprising because this former tow-truck driver, wouldn't be taking his new job seriously.

Point is that people can become angry, and think and say evil and rational things- they kick TV sets, they can curse inamimate objects. The condition of being civilized is most importantly being able to control one's emotions when it's appropriate. Faced with a situation in which a reporter may ask how one feels about some particular thing it may or may not be appropriate to express irrational ideas. Get a bunch people together and add a tiny amount encouragement and as a mob, they can do extremely irrational things.