I agree! it was a little disappointing that I was unable to date Horace. I thought I heard or read somewhere that there was an unlockable that allowed a romantic relationship with Horace...? Or some kind of drink mixture? I tried as many combinations of drinks as I could, but not getting any new dialogue options with Horace :/
But I'm pretty sure there must be some kinds of secrets with the mixology - why else would it be included in the game, since it's so underdeveloped?