Can someone explain why Aeneas Informant doesn't proc with Salsette Slums , when Salsette Slums doesn't proc the abilities of Hostile Infrastructure and NBN: Controlling the Message ?

If he's saying that using slums = trashing a card, then he's changing those interactions.

Unless I'm misunderstanding something, this UFAQ reads like either boggs messed up here and it should proc, or he unintentionally changed the effect of slums on hostile infrastructure and CtM....

4639
The card is always trashed. —
The card is always trashed. Things that check whether cards were trashed or not need to know if it went to Archives/Heap to trigger. Things that check whether cards weren't trashed only need to know if it left play. —
Thank you for that clarification @lordofthetoasters. I was unsure of why certain cards worked with Slums and certain cards didn't. —
Actually while functionally identical the explanation is not correct. What happens is this: Hostile and CtM do trigger at the same spot as Salsette Slums. Specifically at the time one pays the trash cost. Salsette procs first because it's the runners turn and then the card is removed from the game instead of trashed. Since it is no longer being trashed and it never got trashed the triggers for Hostile and CtM are no longer valid so their effect fails. This works exactly the same way as film critic and agendas or femme and tollbooth. Now the trigger for Maw and Aeneas happens at a different time. It happens after the "window" the player has to pay a trash cost. But since the card was removed before then it is no longer accessed, so Maw and Aeneas no longer trigger. This is also why Salsette counts as the "first time" for CtM (because the trigger was met but then failed to resolve) but not for Maw (since the trigger was never met in the first place). —