Why is the Foundation containing this?
Glowing mice have been a reality since 2002 (link), so it's not a matter of shattering the public's perceptions - heck, there are serious, real-world proposals to engineer glowing trees to line highways, crops and decorative plants that glow when they need to be watered, and novelty pets that glow just for the heck of it. Just being an invasive species isn't enough either - regular government and environmental groups exist that handle things like that.
You say that "SCP-621 has no direct psychological effects." If you want to give the Foundation a reason to contain these flowers, maybe you should consider changing that.