It's a compiler bug, and it's present in all earlier versions of the compiler. The fault is not limited to XE4. Submitting a QC report is the correct response.
I would not be surprised if Embarcadero never attempt to fix it. That's because you are using deprecated object
. Switch to using record
and the code compiles.
The issue you have uncovered in this question is unrelated to the SO question you refer to at the top of your question.
Incidentally, this really is a case of old meets new. Legacy Turbo Pascal objects, and modern day generic containers. You are mixing oil and water!