Why do that if he wants this to be about respecting a difference of opinion?
And for the record (see astroturf roots) there is growing suspicion that these outbursts are being staged by Democrats, at least some of the time. It takes McCain off of his message he is speaking about and lets Obama slur the supporters of John McCain.
Where is Obama reprimanding P. Diddy for his "Obama or DIE" t-shirt?