brown
(a) Post pictures of boobs and bums and you'll get a ton of likes. That doesn't mean the picture is how the site wants to promote itself. One photographer posts fanny snaps with the eroticism of a road accident, and artistry of an impending smear test but has a cadre of fans who praise his work and shower it with love.
(b) The Picture in question is NOT flagged as adult. It was uploaded yesterday, so it can't possibly be and FPI yet, but the fact it can suggested and is on page for of suggested says no elf has put it in the FPI queue yet. If one of them does, then the views of others come into play; it's the most suited to go in the shop window that make the cut not the "best". Second guessing how the elves think is fun but futile, but I can see a take that says the AJ goes under "good but not suitable"
(c) Don't expect the process to be logical. A group of people who show they would make selections like past ones get to choose future ones. What they see is pretty random, and a lot of suggestions are unsuitable. What the elves happen to bump into is pretty random
(d) I last got the stats about the the turn of the year but of all awarded FPIs
55.42% Are SFW
44.20% Are NSFW
0.38% Are Adult.
However of suggestions that I could see (things only stay on suggestions pile for a finite time)
35.24% were SFW
63.66% were NSFW
1.09% were adult.
Obviously this means the chances of a suggested image getting picked by the elves are best for SFW and worst for Adult, but very few Adult get suggested.