Yes it is the case. The export functionality is quite old for most of the export types.
The DAE and PDF types are relatively new API-wise, and these are the ONLY TYPES that currently allow option hash as second argument. Because Ruby evaluates only
false as FALSE, and all other objects as TRUE, it is most likely your literal hash object is just eval’d as a
true argument for the export summary.
However, I’ve come across a bug in this method, where for a PDF export the method justs fails and returns
false if the second argument is not a hash.
There are some hackarounds for the Windows platform by reading or writing Registry values for the various export options dialogs, but I don’t know if similar can be done with plists on Mac. (I’m told they are XML files, and Ruby can read them, I just do not know if changing them whilst SketchUp is running will have any effect.)
@thomthom Didn’t you have a repo for hacking the options dialog settings ?
Anyway, … you might look at a 3rd party OBJ exporter. I think @TIG has one over at SketchUcation.