For the curious, here's the reason given. Notice the odd wording (bolded)

"We are unable to offer an Other Airline Match since you have been matched to another airline within the last five years."

Not sure how to interpret that one exactly...


edit: actually, that makes a bit more sense now that I've re-read it. I suppose CO refers to status matches as "other airline matches" and the person they meant to inform must have already done a status match within the last 5 years. It sounded odd to me at first, especially since I wasn't expecting it...