Stigweard.

Your argument basically boils down to "we've tried everything else so a boycott must be a good idea".
You brought in the civil rights movement but may I point out, Tommie Smith and John Carlos protested at the Games but did not boycott them.
Your argument effectively said "you must either support a boycott or you don't care about human rights" - like either you support the invasion of Iraq or you support Saddam Hussain.

You have also implied that not supporting a boycott means we can't condemn China - another "he who is not with me is against me argument".
Your argument is full of logical fallacies.

You brought in Hitler - the last refuge of the desperate.

You also stated that shutting off China from the outside world would be counterproductive - so you admit some actions against China would be counterproductive? In my view an Olympic boycott would be counterproductive. We are both against counterproductive actions against China - so there isn't much difference between us.

Therefore I believe you should apologise for implying that I don't care about human rights, I merely take the opposite position from you on a single issue.