re: "What I'm getting from your statement is 'Elves are supposed to be racist'"
Might a slightly less hyperbolic vision of what is being talked about here simply be ...
"Leaders of disenfranchised, racially-based minority communities are some degree more likely than average to draw racial distinctions with regards to people in their community marrying those of races they view as a historical source of that disenfranchisement (I don't strictly know if this is actually true, but it certainly/naively appears to be true, and I think the causal relationship here is clear enough for this to be viable), and that this apparent connection between a figure typically seen in a positive light (disenfranchised minority community leader) and a trait we generally see in a negative light (making racial distinctions in a social context) is the naturally interesting element to include in storytelling"?
Now maybe the bias is coming in here on my end and there actually isn't any even minor correlation here - I'm not a social scientist of any bent nor are social politics of much general interest to me outside of informing storytelling, so I certainly haven't given this any in-depth thought. That being said, I think this is the common conception of many people, and I think the logic behind the notion does hold up without an objective dispersion being placed upon any particular group coming as it does simply from human nature.
(Something akin to "there is a correlation between whether someone treats gunshot wounds or hunts wild game for a living and how people of that career feel about firearms" - it's not an objective dispersion against people who choose either such a career, it's simply allowing for reasonable inferences when the evidence presents itself based on the understanding that we are informed by our experiences and sources of daily focus. At some point we have to admit that those of us more exposed to bias-inducing life experiences are statistically more likely to be biased - and, yes, secretly that's all of us in various contexts.)
So, might it be the case, that if a connection between a type of character (Racially-Based, Disenfranchised Minority Community Leader, or RBDMCL's as we call them in a field I just jokingly made up right now to make myself sound like a more pretentious jerk than usual) and a particular trait (some extra level of distinction being made about humans racially, in this case) is
1) Interesting and a good source for narrative exploration (sources of conflict that occur between real people typically are)
2) Based upon a very potential real world correlation
That there might be some amount of player expectation regarding what their feelings likely are on race? (Not that breaking player expectations is necessarily a bad thing, sometimes it's a great thing, but it is very much a thing, and should be noted when done and used as a piece of contrast rather than the norm)
Now let's be honest, you could write a good character either way. Both a Keeper who does make that racial distinction and who does not make that racial distinction could be reasonable and interesting. However, you seem to be arguing with Shahadem about which directions gets more points for aligning with the social realities of our world, and I think there is a case to be made for someone like the Keeper making a racial distinction at some level beyond another character or the player (whether or not you call that distinction 'racism'), being more aligned to the social realities that we face in our world (or, at least the narratively interesting social realities of such, which does inform player expectation).
To me, while it is of course never objective and absolute, and stories are always carved out of the departure from it to some degree, this is what "narrative sense" is, and while a Keeper falling in love with a non-elf is certainly allowable and reasonable (I take no issue with it being in the story - I romanced Merrill, in fact), I think when Shahadem says "no sense", he is on some level intuiting something about an intentionally chosen departure from that kind of "narrative sense", and that his statement is actually something a bit more than saying "Elves are supposed to be racist".
Anyways, that was just my response to that first sentence of yours. I don't have a lot of interest generally in social muckity-muck, but statements that include such broad terms as "supposed" and "racist", not to even mention generalizing an assertion about a specified job (Keeper) or even character (Merrill) to an assertion about a whole race (which is actually what you just did), typically deserve a bit more breaking down, in my experience. That's how I see it at least.