Canola varieties with the pod-shatter tolerance trait can be safely swathed late — say 80% seed colour change (SCC) on the main stem. For all other varieties, the decision to swath or straight combine should be made at or prior to the optimal swathing stage of 60% SCC on the main stem.
If canola is to be swathed later than optimal (with earliest pods shattering), cut in moist conditions (rain or heavy dew) to limit shattering as much as possible.
Leaving them for straight combining might be the better option so the crop is handled only once. That decision is based on the comfort level of the grower.