I had that thought as well. From poking around various IP law sites, DMCA is purely for copyright infringement, and can possibly open you up to more liability if you try to use it for trademark claims (what this would be), see http://www.lexology.com/library/detail.aspx?g=13f9814f-b56e-... for an example.

If Comcast wanted to take this down, it would be through a trademark infringement claim.

(IANAL, etc, etc)

I was confused if this was something from the real Comcast, so it seems to be a clear case of trademark infringement (but it's not my call, and I may be wrong).

If GitHub agrees, then it would be a violation of their Terms of Service [1], section A.8:

"You may not use the Service for any illegal or unauthorized purpose. You must not, in the use of the Service, violate any laws in your jurisdiction (including but not limited to copyright or trademark laws)."

[1] https://help.github.com/articles/github-terms-of-service/

I wonder if the author can invoke the freedom of satire.

The DMCA doesn't apply to trademarks. This probably wouldn't violate Comcast's trademark anyway, as they operate in different markets.

Networking and infuriating call centres?

Technically, no. However, it wouldn't be the first (or last) time that a DMCA takedown was issued for the wrong reasons. I can't remember specifics, but I seem to recall DMCAs issued for name conflicts before.