Chris, you have to exclude them all (or remove them first). Did you try?:
yum --exclude=rrdtool,rrdtool-perl,librrd update
Or maybe even:
yum --exclude=*rrd* update
Or
db yum_repositories setprop smecontribs Exclude rrdtool,rrdtool-perl,librrd
Or maybe even:
db yum_repositories setprop smecontribs Exclude *rrd*
Or even this:
yum --disablerepo=smecontribs update