Indeed, the mechanical component is far better at recursive self improvement, which is why I wrote:

Of course, in the end it would transition to a fully or mostly machine intelligence, either through offloading increasingly more cognition to the machine components until the organic brains were only a tiny fraction of the mind, or though using the increased intelligence to develop FAI/WBE.

It also occurs that for a 'hive mind' using the enhanced intelligence to acquire the resources to connect more people to the hive mind counts as quantitative, if not qualitative, biological self improvement.