Iirc, the comment didn't have the usual markers that anti-troll or anti-spam software would look for (such as all caps, !!! etc, insulting words, etc). So it would take a later pass with careful reading to catch it, and they're probably overwhelmed already.

Imo it's ridiculous to think that it was deliberately left up in an editorial decision. At what level would that decision be made, and with what motive?