Seems like a good court argument too—no destruction of data was even attempted because I know I have my iCloud or Google backup. Personally, my phone has access credentials to information, but not the information itself. So you need a serious warrant before you can get those access, but the data is there.
I agree that it seems a simple argument for any competent lawyer to make that the phone isn't the "gold copy". The phone is just an ephemeral copy of the real data which is safely stored away in the cloud, and the authorities can request access to with the proper warrants.
Of course this argument will only work if the phone is indeed and a ephemeral copy of your real data.
Honest question: Does a wipe just wipe what's on the phone, or does it also tell the cloud to delete stuff?