Disagree. An AR-10 chambered in .308 could produce similar, if not better results given, A) gun is of quality manufacture, and B) the shooter is proficient with their firearm. The advantage of semi-auto over bolt is rapid follow up shots. Even an AR-15 chambered in .223/5.56 is a better option than an old bolt gun at that range. A shooter will have an easier time finding a suppressor (if desired), properly mounting scopes, and transporting the weapon to and from the location. An old surplus rifle converted into a hunting rifle might be easier to get a hold of given location, than a AR-10, but an AR-10 is a better weapon.
The ability for rapid follow up shots is the single best reason to choose an AR platform over a bolt action. The Trump shooter killed one, wounded several with an AR platform. The Kirk shooter got lucky with the first shot given his clear lack of knowledge with guns. As unfortunate as this is to say, had the shot been a little more to Kirk's left, it would have missed him completely. At which point a follow up shot on a moving Kirk, amongst thousands of moving people, all while dealing with the adrenaline dump of trying to murder Kirk would be next to impossible for the assassin; and Kirk would still be alive.
Don't get me wrong, bolt action guns can be a lot of fun, but you use the right tool for the job.