Originally Posted by minorhero
I think there are two issues here and its useful to separate them for purposes of a discussion.
1) A law was/was not at some point broken
2) Ownership of smuggled frogs/frog progeny encourages/does not encourage future smuggling
A useful distinction. I'd like to add one more consideration, though:
3) Ownership of the offspring of smuggled frogs is itself morally wrong, regardless of future effects even if those effects are positive, because an egregious moral violation in the past makes this act in the present possible.
This is at least part of the presumptive reasoning behind, for example, museums refusing donations from the Sackler family.