Tesco Samoa and Fyron
So, it is possible. And exploitable.
Your comments seem to imply that this may be one of the 'grey' areas which may be improper to exploit.
I am just a newbie on this, but my thoughts are there is a difference between unethical conduct and an aspect of the game that may not be possible or practical in real life but is possible in the game.
Like hacking the code or playing two empires in the same game is clearly unethical.
In real life a mothballed ship cannot be upgraded. If you upgrade it, it can no longer be mothballed.
Yet the game allows both to co-exist.
Personally, I do not think it is unethical to exploit something in a game that is impossible in real life.
If we do not like it, we can ask for a code change or declare it illegal for use in a game.
The latter clearly presents some problems as discovery of the infraction will take some time if ever, and the damage has been done to some of the empires.