Generic Approach question: Developers with overlapping Development Environments

I run security for a decent-sized company, with several developer groups.

One of them is. . . problematic. Lead insists we allow his team of 6 to manage their own laptops. But wants us to "upgrade the shaky infrastructure". In the process of developing the systems, find that his 6 developers use 3 different Java Development Environments.

Any opinions as to whether this should be allowed. Lead says "they like it that way". I already know I'm going to have to bring the lead (and his team . . .) kicking and screaming into a managed laptop solution, but my 'spider-sense' tells me that there's something wrong with overlapping Dev Environments.

Any opinions out there ? Usually, I trust my hunches, but cannot find anything to suggest that this increases my network's vulnerability, especially in light of the unmanaged laptops. . . .