Your real nose always covers some part of your visual field, still it doesn't bother you, because your brain removes certain stimuli that persist over a long period of time.
Don't be tricked by that "area".
I admit I haven't tried it but, from my experience with the Oculus, you will barely able to see that nose (unless you actually try to look at it, like you would in real life). That area is mainly in the peripheral vision.
I agree with you. The impact of these findings is greatly overstated by the headline, and you make an excellent suggestion regarding a competing explanation about why it might help.
Next study: repeat the study using a "nose" in the outside, or of varying sizes, and see if it helps.
This research is interesting, but it's not front-page interesting.
You decreased sickess by 13.5% by covering up about that much of the screen.