I've read that entire piece (and I'd encourage any who doubt me to do the same) and nowhere in there does Mr. McElwee (who apparently wrote that article in 1967) provide a source for his claim of a "false inference" being found. That appears to be nothing more than McElwee's own individual conjecture as to why it was changed. He offers absolutely no evidence, no link to contemporaneous statements or Congressional records, to support that claim.
Looks to me like Mr. McElwee just didn't like George Romney, and wrote that article to argue against him being eligible.
If you believe me to be mischaracterizing this, please identify specifically the evidence that Madison believed there to be a "false inference". What contemporaneous document contains that proof? Again, here's the link for anyone who wants to check for themselves. The key language regarding the desire to correct a "false inference" is contained on p. 10.
http://natural-borncitizens.com/nbcfiles/nbc_McElwee.pdf
I'm currently reading the annals of congress for 1795. I'll get back to you.