The right-lower part of the character in the evidence looks like "夊"(U+590A).

KR will change lower part to 夊(U+590A).

Although the right-lower part of the character in the evidence looks like 夊 (U+590A), it seems to be the convention of Korea to adopt 夂 rather than 夊. E.g.:
Code chart:

Unifiable with 禝 (U+799D) per KR Normalization rule 11-4.

Disagree.
KC-07659 is used historical place name in Korea.
This character is exceptional case of KR Normalization rule 11-4.

I guess if KR Normalization rule 11-4 is suitable for normalization, we need to know or prove they are real variant with the same meaning; if not, it's better to keep them separately. Therefore, when Yifan or other expert hoped to unify KC-07659 with 禝 (U+799D), he or other should provide the evidence or explanation to prove they are variant.

The text is a part of speech given to gwageo passers.
https://dl.ndl.go.jp/info:ndljp/pid/991068/28

The passage 「杏壇、槐市，增多鼓篋之徒。米廪、禝（稷）山，蔚有横經之子。」
describes the flourishing scholarship in ancient China (or as a metaphor), where all 杏壇, 槐市, and 米廪 are historical seats of learning in China. Hence the last 稷山 should also be a metonymy for a Chinese academic institution, namely 稷下, rather than a Korean place name. As a result, the character must be a synonymous variant of 稷.

WANG Yifan gave a accurate judgement. 杏壇（孔子講壇）、槐市（漢朝書市）、米廪（魯國之學）、稷山（齊國之學） are the names of ancient seats of learning of China， 鼓篋、横經 are ceremonys of Confucianism，so KC-07659 is truely a synonymous variant of 稷.

Since this char is used for a place name, KR suggests that this char not be unified.
KR will add a general principle in KR Normalization Rules doc. that, in general, chars used for personal or place names (proper nouns) are not necessarily subject to this KR Norm. Rules.