The 27-year-old caused controversy at Trent Bridge as he edged the ball to Michael Clarke at slip, only to be given not out by umpire Aleem Dar as he stood his ground, much to the fury of the Baggy Greens.
Flintoff wrote in his column in The Sun: "I was pretty disappointed to see people get their knickers in a twist about his split-second decision not to walk, mind you. I simply did not think it was as big a moment as people made out.
"Broady has done what every batsman should do and waited for the umpire's decision. It happens all the time in Test cricket. Ask anyone in the dressing room — they will tell you he did the right thing."
The second Test begins at Lord's on Thursday.