My take on this is that an important part of stopping the spam flow is to make it unprofitable to send spam. Taking out a destination URL could easily render millions of spam emails sitting in people's inboxes useless and take away the profit the spammer could have made from sending them. I think forcing users to manually edit the source of messages to make them parse is only going to reduce the number of effective reports that work towards that goal.
This particular spammer seems to have a lot of hosting at one company and the sooner they become persona-non-gratia there, the better I think it will be