Censorship of comments

Twice this week, I was motivated to post comments in response to posts by Steve Benen, a Washington Monthly contributor.  His first piece dealt with attempts by various states to suppress voter turnout among likely Democratic voters, especially minorities, via laws that require photo identifcation at the time ballots are cast.  Logic told me that in order to make a link between the laws and the suppression of voting by minorities, there would need to be proof that minorities who are lawfully entitled to  vote are less likely to have/carry photo identification than non-minorities who are lawfully entitled to vote.  My comment read as follows:

Oops, it has, like my follow-up comment, been deleted, but the first response to me is still available:

"And not to hog electrons on this post, but [] you must be f'ing joking.
For instance, minority populations (of any age) tend to be concentrated in more urban settings, where mass transit is available. Whether because of income limitations or sheer hassle of parking, they tend to have fewer cars (and if it's a one-car family, you can be sure Mom and/or Dad use it to get to work).
According to the website Useless Facts, one in four people in the U.S. have never flown on an airplane (http://www.angelfire.com/ca6/uselessfacts/survey/001.html). So I guess they've never had to wrestle with TSA's photo ID requirements.
And while the number of people who do or don't have a passport varies widely from state to state (http://blog.cgpgrey.com/how-many-americans-have-a-passport-the-percentages-state-by-state/), in 33 states it's less than half the population."

I responded (a comment since deleted) that what Blondie (the screen name of the publisher of the responsiv comment) offered was not proof, because proof that poor people aremore likely than others to use mass transportation in no since proves that they are less likely to have photo identification.  But, as noted, the link to Benen's article no longer includes either of my comments, neither of which was mad or angry, and neither of which included any offensive language.  And, I know why they were deleted.  My questions force Benen (and his followers) to ackowledge the reasoning that underlies their argument, and they don't want to do so.

The next day, Benen posted in response to the requests of Dick Cheney for an apology from the Obama administration.  I commented (again I was deleted) that if the President has the authority to kill--without a trial or even an indictment--an America citizen for words he has said in internet remblings and broadcasts, then, a fortiori, he has the authority to arrest a non-citizen terrorist and to use enhanced interrogation techniques and/or indefinite detention.  Each of these were things against which Obama railed as a candidate, so, I agreed that Obama owed Dick an apology.

I guess I dont understand what purpose is served by deleting comments designed to encourage debate.  Here's is what was said at the bottom of the comments section:
"A link from a right-wing website brought the trolls out of the woodwork, leading to a wholesale deletion of comments and turning off comments on this thread. --Mods"