Before you accuse Comcast of lying, you should define what you mean by "block" traffic. Comcast has stated that they merely delay bit torrent, and there is no evidence to the contrary.

Want an analogy? Suppose there were a popular nightclub called "Comcast". At peak times this nightclub is absolutely packed and customers complain about slow service and long lines for the bathroom. The owners of "Comcast" are worried they will lose customers due to the overcrowding, so they hire a bouncer to control the crowd. This bouncer "blocks" customers when the club is nearly full and doesn't let anyone in until someone else leaves the club. The bouncer is indeed blocking people from entering the club, but the reason is to delay customers from going into the club until is less crowded.

I could see club-goers complaining about this bouncer. They will say they are being discriminated against; the bouncer won't let them in because they don't like the way they look or because they might be doing something illegal. Basically, there is no way to determine whether the club is lying about the reason they are using a bouncer; but is there any sensible reason they would turn away customers if the club wasn't full?