I had a similar problem yesterday. I accidentally deleted my os without replacing it cuz im a noob. I was stuck on the boot screen with the padlock.
I went into panic mode and upgraded to kitkat. It worked, but I wanted root, and safestrap. So I followed the method that you linked, and it successfully restored me to 4.3 with root access.
In short, it will work, but it will wipe your phone. And it didn't trip knox for me.
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