Hmmm are you sure you didn't connect out of order?
I just checked and that file is still missing for me.
Maybe I'll try the whole process again after I restore the file.
At what point do you reconnect to the phone? It seems to restore the file almost immediately upon reconnecting the phone, or if the phone is connected when you delete the file it is immediately restored.
I tried reconnecting to the phone at several different places in the process. I tried leaving it plugged in the whole time, plugging it in before booting into recovery, plugging it in immediately after clicking on recovery, etc. I also tried clicking and unclicking the card in several different points in time. I just couldn't reproduce it.
Here's what I just did to test for the usbstor.sys file.
Turned off my phone.
Powered on into recovery.
Plugged in.
Power button.
Down vol then power button.
I f5ed my system32/drivers folder to see if that file would come back anywhere in the process and it hasn't.
Are you sure you didn't plug your phone in while it was on?