you're missing the more significant reason why. Both independent claims have the following requirement:
wherein all of the text of the document is stored within text elements such that only the text of the document is contained between start text tags and end text tags; wherein there are no intervening tags between each of the start text tags and each of the corresponding end text tags
This means that document formats that use a HTML-like mixed content model to do their formatting aren't affected by the Microsoft patent, and that includes ODF.
That's a very good point; thank you for pointing this out! I've added a link to your comment at the bottom of my article under "Notes on feedback from readers".