Unmovable is a little too much, but I guess even if a team need a scoring leader and bet on his health it won't be for more than a 0 value (with salary cap or expiring contracts), maybe even a negative one; I wouldn't thought that if he would have played the Nets serie like he played the last part of the season.
So maybe waiting he is doing a good begening in next season -with one/half years left-, hopefully with Rob staying healthy and some youth progress, could be a better timing, with even a TPE for Fournier, for (hopefully) doing one big trade. Not ideal with the new structure to begin the season with some holes, as it is what we are doing since 2 years, but maybe it will be the best for the future to optimise the value of our guys. Of course I would prefer a solution that could bring Beal or other(s) without loosing the Jays duo this summer, but don't know if it is possible.