Well we just have different beliefs on it being "my" game world 
I respect that there may be players who don't like the fact that I have aliens invading from Uranus
To disregard their opinion or philosophy isn't something I'm willing to do. OTOH, if all the players in the group are cool with it then it's all good.
But to say that you can change the rules and setting willy nilly without giving respect to player's opinion is in my opinion playing God. Is it my "right" as a GM? Sure, just as it's a "right" for players to not want to play your game
After all, many players bought Shadowrun books because they want THAT world.
All part of the balancing act

But if players want just '
THAT world' then you're actually
limited to
just what's in the books.
The books have no Awakened AI's, rendering this entire discussion invalid

If you want to continue
ad absurdum, then yes, the GM is indeed playing God, every session at every table.
- How many SWAT members attack the team?
- Do they have APDS?
- And a Tank?
- With a Rigger?
- Who's an AI and also a Gunnery guru?
- And has a spare nuke with Itchy trigger finger?
These are questions that come from the imagination and creativity of the GM.
- You can be a laid-back, easy-going god and only give them scenarios the PC's can handle.
- You can be a monstrous, chaotic and vindictive god, punishing the players at every turn and using metagaming pizza-shortages to inflict in-Game pain.
- You can be an impartial, fair and encouraging god who impartially rules on an defined set of mechanics, giving challenging but never insurmountable scenarios for PC's to be challenged by.
All of the above are valid. And here's the rub.
All of the above can be ENJOYABLE
It depends on your group. I've had a group that were ultra-strict on schedules, time-per-PC-per-turn, and in-game expected to be hunted down and killed at every turn in an incredibly dark Shadowrun campaign. And they
LOVED it. As GM, I was always worried I was being too harsh, but they lapped it up like a classic Samurai movie, with PC sacrifice (holding the line), torn to death by dogs, and even ritual Seppuku just three examples of how some of the PC's kicked the bucket in this MEAT-GRINDER campaign. And out of character, they expected combat to be snappy, and if anyone took more than 10-
SECONDS to determine a course of action, they forfeited their Initiative Pass. Was intense....
So, yes, it's your world. You can change it as you wish. And it's up to you how 'happy' you keep your players in doing so.
And yes, there have been silly campaigns where the oceans turned to custard. Ahh, the early teenage years where aliens from Uranus was the highest form of humour....