No, it isn't facile. It's simply the most honest route. There is no historical knowledge as to whether Thomas Jefferson was the father of any of Sally Hemings' children. Were you aware that almost nothing is known about the life of Sally Hemings?
While no final definitive conclusion is possible given the data, the data do give a clear indication of probabilities and possibilities. To give equal weight to the probable and possible is something of clever magic act and is disingenuous.
"Probabilities" are irrelevant in judging an historical case. Speaking of them in a historical context is pseudo-scientific. One tries to sound scientific and rigorous, when in fact one is simply indulging in speculation. Now, that's facile. But probabilities are useful in writing realistic, historical fiction. Possibilities are useful in writing historical fiction with little realistic foundation. There, I made the distinction. Happy now?
As to other issues..
I would characterise the Jefferson in Paris story as " unsupported by evidence" thus it is highly improbable. A theory/speculation unsupported by evidence is not a lie unless you can provide conclusive data to deny the assertion. The inability to provide that data to deny the assertion is absolutely no support of the assertion itself.
The Jefferson in Paris story is either true or false. To say it is "highly improbable" is a dodge. I wouldn't have made a point of noting this, had you not gotten nasty, but this "highly improbable" talk is truly shows a lack of courage. Saying it's "highly improbable" doesn't foreclose on the possibility it's true.
The Jefferson in Paris story was built on claims that have been disconfirmed, and which were entirely fictional.
Claim #1. While in Paris, Jefferson bedded Hemings. (Cannot be confirmed or disconfirmed; comes from a confirmed liar; thus, no reason to believe it happened, and good reason to believe it never happened.)
Claim #2. While in Paris, Jefferson impregnated Hemings. (No record of said impregnation, no reason to believe it happened, and very good reason to believe it didn't happen.)
Claim #3. Shortly after returning from Paris, Hemings gave birth to Thomas Woodson. (A. No record of Hemings ever giving birth at the time. B. Descendants of the former slave Thomas Woodson were definitively excluded as descendants of ANY Jefferson male. C. Biography of Thomas Woodson provided by his descendants is full of holes, independent of the Paris story. D. Descendants of Woodson have pushed this story even more passionately, since it was disproven, than before; ditto for academics and journalists.)
The entire Jefferson-Hemings story is built upon the Jefferson in Paris story.
The Jefferson-Hemings story, beginning with Jefferson in Paris, was invented by a known liar, James Thomson Callender, who had no direct knowledge of the goings-on at Monticello, much less those thousands of miles away, in Paris. The myth has been perpetuated for 201 years by people who simply repeated Callender's lies.
The 40 year monogamous relationship is highly improbable and is generally adhered to by those with a very active imaginations and a fatally romantic twist of mind. Whatever charms Sally Hemmings may have had she remainded "property" in her lifetime.It is extraordinarily difficult to imagine a 40 year monogamous love match between Jefferson and a person who was his property. It is even more difficult to imagine it in the context of the intellectual gulf between the two.
This is all empty speculation on your part, which is on the exact same plane as those who say, "Jefferson was so virtuous, he couldn't have been the father of her children."
Throwing around words like "probability" is no substitute for rigor in the handling of historical evidence and historical arguments.