Scott its worth mentioning, but be cautious about how you report it. You can certainly have corrosion without a leak. Galvanizing is a way to provide a form of cathodic protection to the pipe. The galvanizing (zinc) is a sacrificial anode. Its purpose is to corrode, so as to provide protection to the steel. Electrolysis can occur when you have an anode, a cathode and an electrolyte. The electrolyte can be dampness caused by sweating of pipes. I cant tell by the photo, but you may also have two disimilar materials (copper and steel) causing the corrosion. A lot of times you see corrosion at the threads due to the threads being field cut and not receiving any protection. Basically when they cut the threads they destroyed the zinc coating.
Products like ZRC exist for this purpose.

Old galvanized pipes are prone to leak from the inside out, but usually this shows up on the pipes serving the hot side first. As far as replacement goes, I wouldnt make any kind of recommendation like that. I would just report what I saw and let the client make the decision of replacement is required. There are some companies doing internal liners on steel pipes with pretty good success.