The key word here is "capping". People are assuming for some reason that an estate tax means the repo man comes and takes all your earthly possessions after you die or something, but no one's suggesting that. They're suggesting putting a cap on how much you can pass down in an inheritance, as a way to prevent the hoarding of wealth by a single person/family.
If necessary for the inheritor to meet their tax obligations, sure. I'm sure there's a dozen different estate tax systems in place that tax professionals would know more about, but yes, liquidating assets would be one way for an interior to meet their tax obligations.
You would be charged a tax proportional to the value of that business. How you pay it is up to you. This is how estate tax is currently done in the US at the Federal level. Again, I'm not a tax professional, so if you want to know more I'd suggest looking into it yourself.
That would essentially mean family businesses, at least past a certain size, would be impossible. Or more realistically, they would just obfuscate the ownership structure.