The MPAA represents companies with a combined market cap of $250 billion dollars. That's small enough for us to beat, but Pfizer ($150bn market cap) and Microsoft ($220bn market cap) are also major proponents. All together, there's a LOT of muscle behind this act, lobbyists alone aren't going to cut it.
For years these industries (software, music, and video) grew to massive size by exploiting cheap duplication of digital goods and control over distribution channels. Now that further advancing technology has brought duplication and distribution to the masses they are franticly trying to regain control.
The opposing tech companies sell services and advertising. Copyright infringement largely doesn't affect their bottom-line and these proposed measures will be costly for them to implement and legally difficult for them to follow.
Its members are made up of mainly non-web technology companies that sell expensive products and are worried about piracy or counterfeiting of those products: Oracle, Microsoft, Adobe, Intuit, Symantec, etc. Conversely, they don't run user-generated-content sites like YouTube or Facebook, so aren't worried about the problems with weakening safe harbors.
GPLv2 does not contain the explicit patent grant that are part of why GPLv3 was created. And I very much doubt the courts will consider "or later" to include the patent grant.
The code in question seems very peripheral (something about using Firefox for configuration), and have received zero comments on the developers list. I would be very surprised if Microsoft had any other motivation for the release, than to make the engineer who worked on it happy.
However, it is probably not an accident that they choose the version of the GPL without a patent grant.
Also, unless I'm very wrong, the terms "GPLv2 or later" means you can use the software under v3 if you prefer to use it that way. The only way to block the explicit patent grant (but stay will the implicit one) would be to license it under plain v2.