I'm a security guy but like to develop as well. I'd apply for a job in Perl any day, despite not knowing it very well and Python being my main language. But I guess it's easy to say when I just read that you're having trouble hiring, as my expectations of entry requirements are now different. Anyway, it's a shame you have to make such a big change for what shouldn't be a big deal. The language is a tool -- I've even written C# in Visual Studio on Windows 8 for a year in two different companies, which is about as Microsoft-oriented as you can get (I'd rather use something Linux-based). Unless there are major deficiencies and the team is looking to move away already, it shouldn't be a problem to adapt to the team's standards.