Yes, the basic idea is that if a founder has, for example, 25% of the equity in the company but is subject to a 5 year vesting they just don't get the shares that would have vested after they leave. If they move on after 2 years, that is 15% of the company that is no longer outstanding equity and therefore everyone else's stakes (VCs, other founders, employees) are proportionately larger.

In the original AVC post he hints about this by talking about doing the right thing and accelerating the vesting in these scenarios, but that could obviously mean a lot of things in terms of actual amounts depending on the situation.