The statement below is false.
The statement above is correct.
I think you should have a look at the FAQ, for these and many more possible questions
Q: Can “Salvage Operations,” the Mentak’s race-specific technology, be used to rebuild a destroyed War Sun if the Mentak do not have the War Sun technology?
A: No. You may only build a War Sun if you have the War Sun technology.
Q: Are there any circumstances when a player can build his flagship outside of his home system?
It's available on the FFG support site.