I would have thought that with the constant selection of a second all-rounder in Broad this indicates the exact opposite. He only appears to be there in case the batting or bowling stuffs up bigtime somewhere. The only time he has really justified selection in this series is the last test where exactly this happened. Considering England have the longest batting lineup in International Cricket - Swann would have to be the best No. 9 in the world and I can't see Broad as England's No. 5 bowler he can only be considered as the most conservative selection of all!
England has consistently picked 5 front-line bowlers. Maybe not very good ones, but that's beside the point. They've all bowled a similar number of overs. At Headingley they might have dropped Swann and played 4 quicks and an extra batsman like Australia did, but instead they played 5 bowlers.
Now, in your original post, to which I was responding, you suggested that Australia could play
3 bowlers plus a selection of part-timers (none of whom has bowled any significant amount of overs). If you reckon that England have shown any signs of being as conservative as that, I think you're barking up the wrong tree mate.
As for Broad, I'm sorry but I just don't get what you mean by saying "he's only there in case the batting or bowling stuffs up". He's bowled more overs than anyone bar Anderson. He, like everyone else in the team, gets a bat (and has duly contributed with the bat, not least in a potentially crucial half-century at Edgbaston). So I just don't understand what you're trying to say, sorry.
Besides which, to echo GIMH, it's not as though there is a queue of world-class fast bowlers that Broad's keeping out of the team. He's England's joint top wicket taker and second in the bowling averages.