Yeah found it after posting the article, although I wouldn't say it contradicts the story (except for the title), this is my interpretation: random DEA agent sees something [1] that looks probably illegal during a visit and notifies Monticello, Monticello then attempts to confirm this with DEA through more official channels, who then clarifies that it is technically illegal but they wont persecute, even then Monticello decides to remove the plants and seeds [2].

1- `A DEA man noticed the store was selling packets of "Thomas Jefferson's Monticello Poppies."`

2- `Nobody told them to do this, but, under the circumstances, no one dared risk the threat`