No. Unless I am mistaken it was taken with a 1.8 as indicated on top of the photo......
I'm pretty sure the f1.4 lens can be set at f1.8, too. If he had posted one at f2.5 would you assume it was done with the 50mm f2.5 macro?
from the EXIF:
Aperture = ƒ/1.8
Max Aperture = ƒ/1.41