I've seen Amberlink pullets/hens splotched in red brown. Seriously, it was hard to tell! If he were a male sexlink, he would have been a white downy chick. So, I'd go by the comb, entirely, at this point. Sadly, it's not sounding good if it's growing day by day...:(
Pineapple is most likely an Amberlink or Tetratint which is why the coloring doesn't make sense for red sex link. These are wing feather sexed. You may have a missexed male (it does happen) OR you may have a female that is developing like a Leghorn (considering the high % of Leghorn blood, not...