Two quick reasons Afridi’s behavior is very, very bad: first, Pakistanis have had to endure charges of ball-tampering (especially from clueless Australians) since they perfected swing bowling in the 1980s. This won’t do their argument any good.
Second, Afridi has done this sort of thing before (and was caught by an eagle-eyed Kevin Pietersen). Here’s the video:
Ducking Beamers: A Cricket Blog 