What limits charging is the power that the cells can accept, not the fuse. (A battery cell can accept less power input than what it is capable of getting out; whereas the fuse does not care which way the current flows.)
A fun calculation : taking the 'old' fuse limit into account and a low pack voltage for the 85kWh battery yields a maximum power through the fuse at 350V * 1300A = 455kW. Clearly, that's not the bottleneck for charging !
[Edit :] As randompersonx said, the 1300A rating is burst, not continuous, so my calculation is moot.
Anyhow, I do not believe the 'old' fuse is what limits supercharging at 120kW, but I do not have any evidence to back this up.