What do you mean 'legitimate purpose'?
"bypassing DRM for legitimate purposes, such as library access, personal use and format shifting, is unquestionably a legal right, as stated clearly by Section 4 of the new copyright law."
How can anyone know if the tool their distributing is for a 'legitimate' purpose. They can't control or even tell who is using it for what. Since it only takes one 'illegitimate' purpose for any DRM circumvention tool to be illegal, then all the DRM anti circumvention tools are illegal.
It's meaningless gibberish to permit something for one use but not another as though the person can control how it is used.
A crowbar is a lock circumvention tool that is also damn useful for levering planks off nails. The crowbar supplier cannot control people who use that crowbar and so cannot ensure it is only used to prey planks off nails.
This is an idiot law, and the challenge is valid and necessary. DRM does not work, the companies that were pushing it are abandoning it, and breaking bad DRM exposes the weakness of a badly made product.