Its made clear in the news article that they are going to be changed after the event. Its being advertised for exactly what it is and what they change too after the event ends:
The TailSpin event itself is an April Fools fun mode. The Profile icon rewards you can unlock are unique to the event and will remain unique, but will be changed to something more fitting of War Thunders context, whilst keeping the overall style of the pilots. They will however be the unique reward and obtainable in this event only.