I hear you but then why do people have a more negative reaction to ideological based killings like San Bernardino then people like Roof? From my POV terrorism is terrorism
False. Roof was universally condemned. San Bernardino raised real possibility that the line about America's Muslim community somehow being better than Europe's Muslim community due to American tolerance is completely false. Only difference between European Muslims and American Muslims is that there are fewer over here. The best policy to reduce terrorism isn't community cooperation but instead a simple numbers game.
As to Roof, not much to say. What he did was so obviously wrong. Even segregationist racists would have thought it evil. He appears to be a one-off unconnected to a larger trend of similar actions. Syed Farook is a part of a larger trend and a sign that the wave is getting worse.