https://www.merriam-webster.com/dictionary/aegis
There's a button you can click to hear it pronounced. It's a word that already exists, so its pronunciation isn't subject to debate.
The new ship is called the Hammerhead, but because I invented it (which I didn't), I'm going to pronounce it "Ha-mjtld-goo". No.
The Ancient Greeks, who founded the term as Aigis, the root of the word, didn't pronounce it that way and they came up with it.
The modern pronouncement has only been around since the 1700's, thats only 300 years. The game is set 900 years in the future so there is a high chance that pronunciation will change again, perhaps two or three times over especially considering we'll have whole other alien languages to influence the human dialect, not just other countries.
If the whole of the human race vanished tomorrow language and all its constructs and formalities would be nothing but the scratchings in the sand of a toddler, that gets washed away by the tide.
If an alien came from the stars to the Earth devoid of humans they may be able to get the
meaning from the written word, but work out the sounds that it had spoken? Perhaps with recorded sound, but when a modern day example of French has a J and G sounds reversed for those letters, The German V is pronounced W etc, ET 'aint got no chance. I use the French and German examples, but for a person speaking those languages it is I who is pronouncing them differently.
Science is only correct until the next great discovery disproves what went before it, Language? Constantly evolving, never set in stone, unpreserveable.