Some other source code processing tools, with names such as "GCC", "Clang", "Microsoft Visual Studio", "Oracle Studio", "HP aCC", etc., don't seem to have a problem with that file, so I rather strongly believe that this is a deficiency of Source Insight, even if it's not technically a "bug" (perhaps they just have some hardwired limit in the program, so that it's "by design").
And given the number of "Fix: C/C++ ... parsing ..." items in their change notes, I wouldn't be at all surprised to find that it's Yet Another Bug.
How to solve this? File a bug with Source Dynamics and tell them you won't buy any more licenses until they fix it, and use some other tool in the interim.