In fact, it is not ironic at all. The idea is good, even if the man is not. Just further proves my point. Ironic that those good ideas allow us to choose what to do with the statue.
For it to be irony, the statue itself would have to express the good idea... which it does not. It presents an idealized image of a man (created close to 200 years after his death) to commemorate a completely different thing. The piece was commissioned to recognize Jefferson's defense of religious freedom ... which even you, in defending the statue, have failed to equate it with. A far more powerful and appropriate statue would have been a ring of religious symbols with Jefferson's face in the center of them... arranged around his head like a constellation. That would at least demonstrate the idea the man is being recognized for. So even on an artistic basis, this plaster cast of the real bronze statue fails to live up to even it's most basic purpose and intent of its creator.