I was there during the 2003 season and I did find some of those freqs used. Sorry, I didn't note which ones or how they were used (we didn't have Radioreference.com back then to submit them too so I didn't take notes).
453.0125 - vendors (mostly, if not all, food vendors)
451.8625 - most park ops, including: guest services, ushers/security, passing word of the "toss a ball is going slow, needs an announcement on the PA"
461.8625 - heard random squelch breaks, but no reAL VOICE TRAFFIC.