I don't think Zipf's law gives you this. It mostly says that common words tend to be short, but it doesn't tell you what proportion of the text will be common words. For example, in English writing two-letter words are found much more than one-letter words.

However, I think you're correct anyway. The right distribution to look at is something like the orange series in the bottom graph on [0]. Eyeballing it, it does look like 3/5/7/9/11-letter words appear more in aggregate than those of 2/4/6/8/10 (49% Vs 44.5%), and longer words are a rounding error.

[0] https://medium.com/@davidxu90/relative-frequencies-of-words-...