Zaheer is also no great bowler. I don't think anyone ever claimed that.
He is the best we have now but that doesn't make him great.
Also, I am not sure why there is so much emphasis on this "average" in case of Shoaib. This is not one of the major metrics for the greatness of a bowler.
Shoaib Akhtar had all of 178 wickets from 46 tests, marked by frequent breakdowns and indiscipline and going in and out of the team. Are these the figures of even a good bowler, let alone a great one? These are mediocre figures.
Also, if you look at the test bowlers with the maximum wickets, you will see several names on top of him with a better "average", people you may have never even heard the names!
Greatness or even being a top bowler needs much more than an "average" of 25 in test.
I grant he was an exciting bowler to watch at times. But lack of discipline, hard work and basic mental toughness meant his potential went mostly waste.
Now, let's take One days. Our J. Srinath and Agarkar among others have a better "average" than Shoaib. Doesn't mean they were necesarrily better bowlers or great bowlers.
He has indulged in a cheap stunt. Frankly, I personally won't care for him so much. He is one of the also rans in the cricketing world in the larger scheme of things. Not sure why he had to open his mouth about the cricketers who have real achievements behind them, not a lot of gas.
I agree with you. He has been childish and foolish in spitting at the sky.