I disagree, but if we all agreed this forum would be lame. Such tests (that examine the seed coat, and all the flesh inbetween) have already been conducted....many times over.
Check out plant data bases, alkaloid data bases, etc. When you start exploring, you will see how extensive they are. And many you won't find online without a membership, but your local university library should have everything you can imagine.
No one makes lists of what plants
do not contain...lists are made of what plants
do contain.
These seeds (ergoline-containing morning glory) have been extensively analyzed since 1966 and they simply don't have cyanogenic glycosides. I don't think it's plausable to assume so many scientists have somehow missed the presence of chemicals so easy to detect.
PS...I do have a source that says they don't contain the glycosides....me! I've done the research and they don't have them.