Relevant excerpt:

    var nullXML:XML = <root>null</root>;
    if (nullXML == null) { trace("Some XML is null"); }
    
    nullXML == null is true!

That's... impressive.

OK, that's a good one.

Is this ActionScript that's doing the weird xml tag interpolation?

I stand corrected, this is definitely possible. Still, I bet this person's real problems stem from explicit coding.