Was there any injury to the tibial plateau or is this now simlpe a surgical site? If no injury then I cannot see any reason why you can't mobilise the knee joint and in fact this might be something I would do during the first session.
You need to keep in mind that the leg suffered a brutal injury to fracture in two places and that often the "fixation" or focus of the acute medical team is the fracture.
Yet to fracture the clients leg probably took a huge force across the knee joint itself. This may well mean that there is soft tissue damage at the knee as well. Assess the knee joint for specifc knee injury and treat as applicable.
Most of your exercises seems fair and well thought out. Graded additions of these though as callous formation becomes more ossified. It is likely that the ankel could well do with some mobilisation and the calf and peroneals with some gentle soft tissue work to restore tissue balance, blood flow, nerve elasticity etc. The fracture itself and the subsequent immobilisation would have had an effect on those areas.
I would say don't do to much to soon. Keep it simple, standardised, work on two legs together initially before challenging balance on one (as they might not have had great balance prior to the injury). Walking alone will be enought for the fracture to heal so you don't need to consider exercises to compress things anymore than that in terms of ossification.
Good luck and keep us posted with problems. How did the injury occur? 8o