Mile stone and float

HI Friends,

There are some dicrpency with my main contractor's planner

the case is,

i said to main contractor's planner that you can use a total float of an activity when the finish milestone is with Zero float. My main contractor's planner is having total float in activity as well as in finish milestone also. i told them to follow early start/finish dates, which will lead to early finish of finish mile stone and if you follow late start/finish considering the total float of an activity, it will lead to late finish of finishmile stone (which has float)  . My contractor's planner said to me that he can use the total float and can delay the activity when the finish milestone with total float.

is main contractor's statment correct.? please clarify