RSA was patent-encumbered for a long time too. You can formulate a similar argument about that. "RSA makes systems safer [ed: no it doesn't, but continuing...], so it's wrong to allow it to be patented".
The step from (1) to (2) seems doubtful. If the CR people hadn't been able to patent a bunch of ways to deal with DPAs, they might none the less have published about them. It's not as if no one ever tells the world about a security vulnerability without a patent-based incentive.
The step from (2) to (3) seems doubtful. It seems more likely that without CR, sooner or later someone else would have thought of differential power attacks and published about them. Unless CR are just much much smarter than everyone else -- in which case, the guys in black hats would have been just as much worse off as the guys in white hats.
The step from (3) to (4) is OK, with the proviso I just mentioned: it seems that the obvious way for (3) to be true would tend to make the vulnerability matter much less.