The phrase 'since as' is not correct and it is not usable in written English.
You cannot use it in any context.
The intention is odd since, as Snowden revealed, they have enjoyed such access for years.
He has lived there since, "as an ordinary man, a member of the South Asian community".
She has not worked since, as additional medical problems have piled up over the years.
This is what I've tried to practice ever since, as a cook and restaurateur.
He has been reconstructing the film ever since, as further footage is unearthed in archives.
Modena needed plenty of work since, as an admitted compulsive gambler, he was constantly in debt.
Kato had felt unsafe ever since, as he battled a siege of insults and threats.
Breakfast has been a magnet for students ever since, as well as the teachers' best friend.
For Toledano, it was especially frustrating, since, as he says, "we never had a personal conflict".
He has worn it ever since, as his mother did, around his neck.
Dance audiences have diminished somewhat since, as has the number of students in many dance classes.
