No. All things being equal, the VC and cofounders leaving is a bad sign. But all things aren't equal: Buffer is so profitable that it can buy out its investors without impacting operations. That's an extraordinarily good sign, one few startups ever find themselves in a position to do.

The Buffer post is extraordinarily clear (almost numbingly so) about the mechanics of their Series A and why they needed to buy their way out of it. They had two structural problems:

(1) the terms of their A round included a strong incentive to liquidate the whole company early, in the form of a perpetual 9% annual interest payment due to the A round investors after 5 years.

(2) the terms of their A round forbade them from extending liquidity to other shareholders, including employee equity holders, without the approval of the A-round lead investor.

Unsurprisingly, Buffer's A-round investors needed to be talked into accepting the buyout, which they took at a substantial premium to their investment in the company.

I do not think the logic you're employing to value these shares is sound. Early exits are usually bad for employees (the lower the exit valuation, the less money is likely to trickle down to employees). Profitability gives Buffer lots of options to maximize returns to long-term shareholders, which is what employees are. To my eyes, Buffer's employee equity is more valuable given this information, not less.