I don't think "old but powerful intiate who's close to death and is willing to make a deal with dark spirits for immortality" is the kind of person you can just find on craiglist. I highly doubt Shedim expect that to be an option you can go looking for. Especially when they're kind of in a desperate position they are now, where they're basically just struggling not to go extinct on Earth.
Why not? statistically there have to be a couple old powerful initiates ready to make that deal, but that said young Ambitious, and wishing to be immortal would work to. Magic Folk lore is packed with such Faustian Bargains. Given meta-human nature, I'm willing to bet at-least a percentage of any MIT&T graduate class would be willing to consider such a deal.
I'm looking at this from a different angle. So first we need someone who's been a magician for decades, and is very powerful. That's really really not common. A full mage is 10 out of every 10,000 people. So that's... What, .1% of the population who were born after 2012. Now remove everyone who was born less than 50 years ago, which considering it's been 78 years, is about 5/8th of the full mages. Now, none of those remaining are explicitly powerful magicians. An accomplished mage is probably what, top 10 percentile? So that's 90% of those mages gone. Now, with our very, very specific magician target existing, let's consider other potential hurdles.
Someone who's been a magician for decades and is very good at their job is not lazing about waiting for a Shedim to pop in and say hi. They're busy, they're deep into whatever corp hired them, or they're an old-ass runner. Regardless, they are inevitably very aware of the Watergate Rift and what happened. Similarly, they aren't ignorant about Shedim, they know how dangerous spirits can be, and they know how dangerous a spirit pact can be. This isn't an ignorant, reckless youth after all.
If, despite knowing about Shedim, the rift, spirit pacts, and so forth, they are
still willing to take a Shedim's offer (instead of a different way, or even finding a different spirit with Immunity to Age, which they have the resources and skill to try and do), the Shedim has to find out they exist at all first, and then find a way to get to them.
This Shedim doesn't automatically become aware of all magicians on the Earth when they arrive, they'd need to go out of their way to learn about them, then contact them somehow. I don't know if a Shedim can use AR while its in a body, but I suppose they could get someone else to do it. They'll probably have to meet up somehow, unless this old, powerful mage agrees to some kind of mystical pact with a stranger he met online.
Suffice to say, it's all technically possible and so works for a singular Big Bad Evil Guy, but seriously this is not Plan A for Shedim.