The Second Amendment was wildly popular.
No one was being "appeased". The colonies had just gone though a revolutionary war where the King had repeatedly attempted to disarm the people.
The other part is context. Slavery was endemic in the world, and had been for thousands of years. The founders were exceptional in they recognized the natural rights of man and put into the Constitution the seeds of the destruction of slavery.
Brandt Robinson did seem to look around and find scraps that would support his thesis: The 2nd Amendment is Racist.
And he reminds me of the typical at-university semi-charismatic machine that captured the unknowing minds that would not investigate on their own.
Thanks for your consideration of his video at Twitter. Figured you might want to know about him.