As far as I know it's only the media who have mentioned tactics, Pietersen has always denied that vehemently. Obviously it being leaked causes disruption to the England team, it would be interesting to know who leaked it. Otherwise it's a private conversation between two mates (and possibly about one particular incident rather than KP's general opinion of Strauss). Are you telling me nobody on here has slagged of their team mates/work mates to their friends? Doesn't mean Strauss and KP couldn't work together, you never like everyone you work with.
I'm not defending KP by the way, he's an arrogant sod who has a massive chip on his shoulder and has made plenty of mistakes. But I think the text thing was blown out of all proportion and in general he's been mismanaged.