Still, given the small size of Nim community and even smaller size of the genomics nim subcommunity, I would say it is not that odd that is not included in the benchmark. The existing nim genomics library might not even cover the functionalities required by the benchmark.
Nim is not really 'pythonic'. It does have some superficial similarity with Python (being whitespace sensitive) but it begins to diverge pretty soon. This is not really a criticism of Nim. I quite like many of the choices in Nim.
Seq claims that vast majority of python programs would work as is. I have not validated that claim, but Nim can absolutely not make that claim. Any python library would require substantial porting effort to be translated to nim.
Calling Nim Python is like calling OCaml or Scala Python, it's not really true. The main reason people use Python is because it is Python, not because of an extractable list of things.