I did. Eldars always have tricks in their pockets. Otherwise I wouldn't focus so much attention of this occasion.
This wasn't clear from your original post on the question, hence the question about how different the outcome ends up being.
With all my respect, Siren's ability explicitly reads after. SM was there before . After ≠ before. At least in my universe. Case closed.
"After" and "Before" what, though? After an opponent's unit is deployed, right? Isn't Siren's ability explicitly working "after" the SM is deployed?
With all due respect, the conceptual problem you are having isn't with the word "after"; it is with the phrase "this planet." You are wanting to set the identity of "deployed at this planet" based on Syren's location at the time of the SM's deployment, rather than setting the identity of "deployed at this planet" based on the location of the SMs deployment.