My suggestion is just to pivot your ruby skills (I assume are web dev) into Python. Make something awesome in Flask - there aren't any real good data science tutorials in Flask which sucks but it seems to be a tool that a lot of data scientists use.
I don't see your point. I don't think so that it's an programming language problem. What can he do if he starts to use Python and a web framework using the new language?
Help build and integrate data tools - this could be done in Ruby but I'd imagine that working with data people using the same language could be helpful.