The reason for exclusions not working is that they're not implemented yet. The vulnerable driver blocking is a separate feature, not based on "regular" scans, so exclusions have to be implemented separately (plus a separate UI controls should be added).
It's going to happen... but for now, you can simply disable the vulnerable driver blocking completely - in Troubleshooting, under Enable Self-Defense. (Since you'll already have a popular vulnerable driver running, it doesn't matter much if you exclude just that one or disable the feature completely - the door for malware is wide open anyway.)