Seasoning, freezing, thawing and then deep frying chicken
Safe? Yes, of course.
Wise? Probably not.
When you thaw the chicken, the surface of the meat will get wet, from both condensation and thawing ice chystals. Yes, proper handling minimizes this, but it can't be entirely avoided. So when you dry off the meat before battering (which you will want to do to make the batter stick), you will probably wipe off the seasoning applied to the surface too. With "wet seasoning" like brine that is supposed to "soak into" the meat, this will be less, but the main parts will be on the surface as well, as Jolenealaska pointed out in her excellent experiment here.


So seasoning when you are ready to prepare the meat is the more efective way - and IMHO you won't be saving time by pre-seasoning if that's what you are asking about.