Some guys don't have a lot of natural upper-lip hair, 'specially when young. I remember in high school and college, a few of my friends got thick beards fairly young but only very wispy upper lip hair until later -- the reverse of the more usual pattern where the moustache grows in first.
I have a hard time believing that a Muslim would shave the moustache but not the beard -- they all seem to prefer full facial hair, or moustache only. Shaving the upper lip but letting the beard grow is an Amish custom.
Yes he did look Amish, or Swedish, or like someone who lived around Abe Lincoln's time.