I've participated in several MLK parades with Knox Dems and though the party often has a float the elected officials never ride on it! While I think Don has made a good statement, I've never seen those guys have any interest in the party's float.
In 2003 there was no party float and several party volunteers who were kicking off Jim Gray's run for chair marched with "activist turned felon" Perry Redd and the Sincere Seven. From 2004-2006 Jim Gray and Delainia Davis and others got a float and or organized a walking group for party volunteers labor people and others. Some rode and some handed out fliers at the end of a tiring walk we would be greated by Diane and Joe ect back-slapping with the GOP down at the church. They never asked to be with us and to my knowledge nobody asked them.
As for that church service I went in 2003. The preaching and music were wonderful but the hypocricy on display was too much, ie: Victor Ashe singing "We Shall Overcome" in Danny Mayfield's church.