Hmmmmm.... I had not read that, do you have a source?
Surely what those "fire eaters" wanted -- who walked out of the first Democrat convention in Charleston, in April 1860 -- they got in their platform, in the rump Democrat convention, in Richmond in June?
Did Breckenridge's platform include the planks you just mentioned?
I may have misremembered the Personal Liberty Laws of northern states as specifically being a big issue at the convention, although they were an enormous irritant to southerners, even though they had little actual effect. To be fair, these laws were entirely unconstitutional. (Which does not speak well for the Constitution.)
But I was entirely right about a federal slave code for the territories being demanded at the convention. When the demand was voted down, the southern delegates walked out of the Charleston convention.
Democrats tried again in Baltimore, and this time the southerners, and some of the northern delegates, walked out over the issue of whether all the delegates who had bolted from Charleston should be reseated or not. The seceding delegates then nominated Breckinridge for President.
http://en.wikipedia.org/wiki/1860_Democratic_National_Convention
The issue is covered well in Battle Cry of Freedom, which I just finished reading. The 3-way splintering of the Democratic Party pretty much ensured Lincoln’s election, which was probably the motive for some of the southern delegates behaving as they did. They wanted secession, and ensuring Lincoln’s election was the way to get it.