It really a good idea to have modern support classes at all AHRMA (&AMA) events. There was 1 support class yesterday at Delta and 8 Post Vintage classes, it brings a bunch of "locals" and spectators, help the promoter pay his bills and certainly doesn't distract from out experience. And from a modern riders perspective it gives beginner and intermediate racers an opportunity to race on a safer/tamer track and have a blast. The real challenge for any promoter interested in Vintage racing of any brand is turnout.
From my perspective these modern riders help subsidize our vintage events.