Probably for similar reasons I gave in my criticisms of OUT, which were both structural in the document, and with signatories of the document. Though really, it's mainly the structure of the document that allows/would allow for it to be used by the signatories in a manner that does not help our own alliances, nor any of our non-orange allies.
Since there's no real economic facet to the treaty, all that OUT is is an ODP. I wouldn't sign an ODP with TOP normally, so why would I keep this ODP with TOP?
Everybody should look into that sometime, except, color means nothing, so we're not all on the same team.