Similar to what I've seen here in Anchorage. Every mountain bike trail sees opposition from people who just don't want bicycles on trails.
Up here the latest argument against them is bear safety. A local biologist -who doesn't want any new trails- has made it his mission to convince people that mountain biking is superduperdangerous in bear habitat. And that the only reason we don't see dozens of mailings every year is luck. He is completely ignoring the data -example: 8 solid years of purpose-buily mountain bike trails in Anchorage without any bear maulings. But between appeal to authority and people not bothering to think, he managed to delay construction of new trails for another season.
One thing I've learned is that, no matter what the project is, if you go to public involvement meetings at least one person hates it. I've seen it at work, when I'm involved on trail advocacy... everywhere. There is at least one person who's only purpose in life becomes to stop that project.