Well, I think there is some logic to it, although I was deliberately going a bit too far for dramatic effect. Involuntary community service is used as a punishment in some cases, and making it effectively involuntary here (or, if you choose not to, then presumably you will lose your benefits) seems to me to have the same effect. There is instead a certain amount of social stigma attached to community service. In some cases, it might even drive people further away from society.
If such proposals are to be implemented, and I can see the point to an extent, then perhaps some form of two-tier system is more sensible. A fixed, but reduced, amount of benefit is given out in all cases, and then volunteering for community service could supplement this. Then it has the feel of a proper job, albeit not a particularly pleasant one.