Watching it last night, I thought The Daily Show was on brand but a little underprepared about the subject. Also, Chang's outbursts of "Aliens" every 30 seconds got a little worn out by the end, it kind of had its place though in order to keep things upbeat. For me it was a step in the right direction away from all the political drama at the moment. Why were you so disappointed?
People pushing overt bullshit should not be given a platform. Even with that sort of mockery, there will be enough people who just see that he was on the Daily Show that feel it gives him an air of credibility. This is the same show serious politicians and academics go on, after all.
It damages discourse. Sure, it doesn't damage political discourse overtly, but it is anti-critical thinking, which damages all discourse.
To be fair, this is the kind of guest the show needs to hold up against more "serious" guests who get up to all sorts of bullshit. Appearing on The Daily Show shouldn't be considered a feather in anyone's cap, save for comedians.
The daily show's job is not to fact check the guests, their job is to help promote whatever product the guests are selling with a veneer of journalism. So he wasn't "underprepared", that implies their intent was to actually get to the truth. The intent is only to give the guests a glorified ad spot.