Nope. They don't communicate (refuse to) though at least they don't shoot my diplomacy ship even tho its been sitting in place for a year next to them.
In 1.0.0, I had a NPR talk to my diplo ship every 5 days for almost a year before they left the system, but we never actually established communications, I just got unintelligible messages that caused an error popup every time.
"Unintelligible communication" is when they tell you to leave your system, but you don't have communications established yet.
Diplomacy ships don't do anything according to the C# change list, if the NPR is "refusing to exchange information". You can't translate their language and begin diplomacy if they refuse to talk to you.
Has anyone so far found and NPR that doesn't refuse to exchange information? I'm beginning to wonder if there is a bug.
I did have an NPR that tried to communicate, but all i got was "unintelligible communication". In the race window i checked the diplomatic points and they did increase very slowly, so in theory communication should be possible. It was in 1.5.1 and got the #1530 error with my diplomatic ship before i got any further.
pretty sure it is bugged/broken as of 1.5.1 - i was getting errors when I had a diplo ship in mutual contact - but i haven't tried it on a newer version yet.
See if you still get the errors with a diplo ship in mutual contact or if it is different.