I agree with what this man is trying to do and more people should be aware of the subject he's talking about.

In the following, I won't be trying to argue against him, I'll just give some corrections so when you use him as a source to build an argument, you'll hopefully repeat the correct stuff and leave out the incorrect stuff.

Napoleon I. died in 1821, so margarine had nothing to do with him, but it was indeed invented in 1869 in France, was made from beef tallow and was meant to last longer than butter.

It became complete and utter poison when made with vegetable oils in the early 20th century

https://ourheritageofhealth.com/the-history-of-margarine-and-why-butter-is-better/

Also, "one molecule" of difference does not confer any information, you'd have to either say "one atom" or "one so-and-so-group", like one hydroxide group. His example of ethanol and methanol, while correct, invalidates his own argument there, because the difference of one carbon and two hydrogen atoms means a good time with one and terrible health consequences with the other.

I have heard about the test of leaving butter and margarine sitting outside for a while and I would really like to test that some day.