Bah, not much in it. Sensationalist headline from Rugbydump. He gave him a bit of a shoulder into the chest and McCaw's head snapped forward and his chin hit off Mackintosh's shoulder. Mackintosh should be more careful but making it out that it's more than that is just silly.
His defence was as good? I'm guessing you forgot to write the 'not' in that sentence because it's really just not true. Maybe he was as good as Ronan O'Gara in defence but that's about it. The fact that he was famous for tap-tackles is a sign that he wasn't able to do normal tackles.
I'd like to see a replay of that as well but my understanding of it was that just as O'Driscoll was going to tackle Brown the whistle went, so he sort of hit him but held onto him and stayed upright rather than following through and smashing him to the ground. Brown then gentlemanly shoved O'Driscoll and then shoved him again after BOD didn't react. I would like to see a replay though because I'm not sure.