The biggest issue Turing has is that it’s really expensive for what you get off-location. Crick may be Yoggable, but it’s only one credit to rez, no big deal, and it’s 2 for Gordian and 3 for Zuul so that’s not terrible for how much it costs you. Meru Mati remains a gear check like Ice Wall even if it’s not a tax, so you can try rushing something or buying time at the very least. Gutenberg is pretty easily taken down off-target by most sentry breakers (and who doesn’t run Mimic) but R&D lock is one of NBN’s biggest weaknesses so there’s rarely a need to consider installing it elsewhere anyway.
Turing as a 4 for 5 on remote with that subroutine makes sense more or less, but it’s only 2-strength on a central, so if you draw it as one of two bits of ice in an opener it’s pretty painful unless you know they’re only running AI breakers. Even then, they can get through, albeit at stupidly high costs.
Turing is also harder to stack on remotes because of the increased cost. A wonderful thing about Gutenberg, Crick, and Meru Mati is that if you draw a second or even a third it’s never awful to just build that server up some. Maaaybe for Crick, if they’re not running Yog, because Archives rarely needs the same amount of defense as R&D/HQ do. But it can go on any other central and stay more taxing to them to run through than you to play.
But I’m happy to pay 3 credits to install and 2 to rez a Gutenberg as a fourth piece of ice on R&D. Likewise Meru Mati, if the need is great. Crick is wonderful most anywhere.
The other thing Meru Mati does is provide hard ETR. It’s probably a mistake for the runner to spend 3 clicks getting through Turing on a remote server, but they can, so it’s not safe enough for me to want to rush an agenda behind alone. If it was unbypassable as well, maybe, because it’d at least replace Guard in some respects, and they couldn’t try to do the Criminal trick of Inside Job to check, then run through because “lol, Guard, I have Mimic”.
If Turing had the rez/strength of Meru Mati it’d be much better. Only a datasucker away from Yogging, but much cheaper, not D4V1Dable, only barely more parasitable on a central, and immune to 4tman anyway making it not a terrible strength for inclusion. Make it cost 3 at that point and it’d still probably be good enough to see real play. At 4 for something that can be easily handled by either D4V1D or Yog, not so much, especially in comparison to the other Ice HB has access to.
EDIT: The stacking thing seems important. Turing is meant to be good on remotes, while the others are early centrals defense, but adding Turing to a remote that’s already got ice there is a huge extra cost. I’d rather put Crick on most remotes than Turing, because it’ll be a nuisance tax and potentially hilarious even as a 1-deep protection if they can’t break it because you can install an ice from archives over it and make them encounter that next if they keep going, or put something else in to protect the server, or build it up for future turns, or whatever. Put a snare in there at the last minute to protect your upgrade, whatever you want.