Won't say I told you so but ...
This was exactly what the Dolphins feared when they reluctantly allowed Williams to pursue a CFL contract while he served his NFL-mandated suspension.
Despite being against this idea from the start, I see there is a silver lining in this situation. It's an arm, for gosh sakes -- not a knee or an ankle, which are a lot more important to running backs.
It is possible that Williams will not play another down for the Argos this season. And that's great for Miami because that means he won't risk another more serious injury. Meanwhile this injury is rarely the kind of thing that derails a RB longterm.
That means Williams should come back to the Dolphins healed in 2007. Almost as important, Williams will continue collecting a paycheck from the Argos, which is the reason he's in the CFL to begin with. And he'll be in a semi-controlled football environment while he rehabilitates the break -- again, a plus for Miami because he's not being chased by some weird malaria bug or something in an Australian outback tent.
So while the injury is unfortunate and we all wish Williams a speedy recovery, I believe the Dolphins would rather he not recover TOO fast.
Only fast enough to have Williams avoid further contact in the CFL and be ready for the 2007 NFL season.