The problem is not because of the array initialization. Indeed, as you say, MISRA C:2012 standard allows an exception of rule 10.3 for aggregate initializations with {0}.
The violation is shown because you are assigning 0 to a float variable (the two have different essential types, see here for essential types). But the MISRA exception for {0} covers aggregates of all data types. So, this is indeed a false positive (and will be fixed in a future release).
