Journal: How to convince a government agency open source is safe?

I'm contracting for a Government agency working out on an editor to help them add XML tags to what they're writing. As an open source advocate, rather than start from scratch I grabbed a copy of TinyMCE, which is LGPL'd, and started writing a few plugins to do the trick. Now that heading toward deployment, it looks like they may balk at the viral terms of the LGPL. This is an inhouse app that will only be available inside their network, so there's no "distribution" problems, right? To me, the whole thing is moot anyway -- I'd be happy to open source the plugins, and I understand that by design JavaScript is "open source" -- but I don't think they do. They're a little more fearful -- even though they use a number of open source, even GPL'd apps, inhouse -- but they don't modify them. Are there any arguments or anything authoritative I can point them to to show them why they need not worry?