Citation2
I think you read the fuel leak procedure in a hurry . First you mistakenly assumed that the procedure requires to switch off heavier side. Now also you are mistakenly assuming that it asks you to balance the fuel if a leak is located and stopped with engine shut down. No! It doesn't. All it says is as below:
If leak stops: ENGINE LEAK CONFIRMED
FUEL X FEED.............................................AS RQRD
DO NOT RESTART AFFECTED ENGINE
True you may have less fuel on the dead side because of fuel leak but nobody asks you to balance. Select your diversion and continue there. When live side fuel becomes less and if you need dead side fuel then open the cross feed and switch off lighter side pumps. The procedure is called imbalance procedure but in this case it is not for balancing. As for as the imbalance bogey is concerned FCOM below:
Note: There is no requirement to correct an imbalance, until the ECAM fuel advisory is displayed.