Its simple really: wikipedia shouldn't be the dumping ground for any and all information--that's what the internet is for.
In this specific case, the only notable thing about this guy is that he invented clojure. Thus he should have a mention or a footnote on the wikipedia page for clojure. He hasn't done enough to himself be notable.
- Purism with respect to Wikipedia policies (I would place this example in this category)
- Ideological commitment to notions about what an encyclopedia "should" be
- Personal vendettas
- ...and so on