Yeah, that one’s definitely shadow counterable. Of course it does require meter - but then so does shadow web cling, her other best option on wakeup. In my experience it’s good to try out the backdash when you’re meterless to see how the opponent likes to pressure you, and then respond appropriately once you have the meter to do so.
Most Sadira’s actually do use shadow web cling quite a bit, even as we grumble about how terrible it is. It’s worthless in the corner, gets blown up hard by many meaty setups, and gets destroyed by neutral jump+button. It’s still a good option in many scenarios though, which is why you see it used a lot even (perhaps especially) at high level. It’s like her backdash to a certain extent - it has a lot of holes, but can be pretty good when used wisely.
As far as worst wakeup in the game? You could probably argue that, though I think with solid oki and OS’s there are a few other characters who are as free on wakeup as she is. Spinal and TJ come to mind, although both of them have strike-invulnerable escape options that they have access to pretty much at all time. They’re both free if you know how to stuff those options though, and their backdashes aren’t good enough to get out of simple crouch+LK’s most of the time. Hisako’s on the list as well - she gets blown up pretty hard on knockdown, and her terribad backdash means she can’t escape even obvious setups a lot of the time.