Can you leave a kanji as hiragana in a haiku?

Question

In my Japanese class, we are writing haikus on Japanese American history, and I decided to write about the Nagasaki and Hiroshima bombs. In the third line, I wanted to leave し as the hiragana because jisho.org shows し as having many different meanings. Many of the first meanings listed have interesting interpretations I thought of, but my Japanese teacher says it wouldn't make sense to a native speaker if I do this, that they'll just think it was a mistake rather than being left for interpretation.

TLDR: Can I leave the し in the third line of this haiku as hiragana to leave it open for interpretation, or is that not an option in the Japanese language?

原爆や / 夕立が落下 / 極暑のし

Nuclear Bombs / Evening Rain Falls / Intensely Hot Death/City/Poetry

Answer 1

After pushing aside questions about why you would doubt your teacher’s explanation and whether you are asking for a bad grade, I have decided to simply provide some information from this site.

Kanji has (specific) meaning.

Recently, ‘sparkling’ names (intentionally unusual names) are all the rage, but in ages past ateji wasn’t used. For example, ‘しんゆう’ can mean ‘close friend’, but also ‘confidante’ and ‘trusted friend’. In the world of haiku, this is prohibited. Rather than using words which only you know the true meaning of, haiku is meant to communicate precisely what you want to say. As a part of Japanese culture, ‘thinking of others’ enters into this, use of unpopular ateji is not recognized.