It's not the law as written, but as it plays out in the larger socio-economic sphere, that is often determinant. It doesn't matter what your rights are, if the other guy can spend you into the ground with impunity.
Taken to extreme, it's one reason we regulate monopolies (in the U.S.). You may come up with a better product, but if the other guy has a lock on the market...
If you don't have the resources, the wherewithal yourself to execute the fight, how do you make it? On your own, your one option is the shop for a lawyer who believe you have enough of a chance that their willing to invest in the effort (in return for a hefty share of any judgment in your favor). If you are fortunate, the EFF or another organization may take up your case and use the pooled contributions of its members to fund the fight.
Even then, what will the publicity do to your career and other aspects of your life, depending on who you work for, etc. Fighting such things, one way or another, is important, but it is not easy and not everyone has the means, financial or otherwise. The means to fight, and/or the means to survive if the judgment (and penalties) goes against them.
Excuse me, taking down a link to a discussion of the key? Does the DMCA really extend that far? If it does, it really sounds like it could be challenged on First Amendment grounds. Otherwise, either this guy has no backbone, or there is more to the story.