The search engine doesn't seem to support the OR operator for body searches:
@Arjan - the [or] was never intentionally supported, and it never worked except in the explicit [tag] [or] [tag2] case, no other operators could be used. It's an artifact of how the redirect to /questions/tagged works, not the search engine...the search engine never handled it. That's not to say we won't support an "OR" tag syntax, it's on my todo after this NY move...along with 50 other items. – Nick Craver♦ Jan 27 '13 at 18:57
Since I haven't seen any feature requests for an OR operator tagged status-complete since then AND the advanced search help only talks about using this OR operator for tags, I feel safe claiming that since Please Join Us in Welcoming Our New Meta Stack Exchange Moderators! doesn't include the words nominated or nomination, it's not included in your results.