I should also add, we have been very clear and up-front from the very beginning that there will be times when we need to place restrictions or make alterations to the site as a whole for the benefit of the service as a whole, and preventing the site from being overrun by spammers is definitely something I think qualifies.

Also: do you really think that someone who hasn't been active on the site in a year or whatever is going to be that upset over the service requiring commenters to solve a captcha in order to comment, when on multiple other services of similar reach and remit, not being active for a year is enough to get your entire account deleted?