I was under the impression it's fine as long as you throw the frozen hop mush directly into the boil and not let it thaw...
That being said I'd reconsider freezing a glass jar for long term storage. Also, I'd still go to the effort to dry hops in the future. It makes using them easier and I think they store better/longer.
However, I think I've read that it's bad to freeze, thaw and refreeze. So I'd let these be and change methods on the future. Just my $.02.
I'd like to reinforce the idea that putting them directly in the freezer is fine.
I'm not sure where this idea of them turning to mush comes from. That certainly can't happen below freezing point. Not sure why you'd thaw them first before brewing either.
I have actually done this before, last year. If you'd like to see documented proof please start here:
http://hopstarter.blogspot.com/2013/09/brewing-pt1.html. No mush was observed at any point in the proceedings and this was quite easily the best beer I've made to date, particularly if measured by compliments from other people.
As far as I can tell the reason commercial growers don't freeze their product is because it's just not even close to being feasible. The quantities they deal with mean they need to have a product that is stable at ambient temperature, same is true for commercial brewers.
If you are neither a commercial hop grower nor brewer and have space in your freezer then I would highly recommend freezing over drying. Drying means they can be kept for longer at room temperature, but you will lose a whole host of V.O.C.s (Volatile Organic Compounds aka flavour and aroma) that would otherwise go into your beer.
If your cones go straight into the freezer after picking and then straight into your beer during the boil you will get to appreciate all this extra flavour that is lost during drying.
Also, just as a small tip, I prefer to put them in ziploc freezer bags and then roll them as flat as possible, a bit like a sleeping bag. This expels as much air as possible and means they take up less space.
You can see all of this and more on my blog.
Hope this helps.