Making a choice that led to the entire management team leaving is tough, no doubt. Making any massively unpopular decision that leads to some of the smartest people working with you to actively flee your enterprise would be hard for anyone.

That being said, there is something to be said about how this comment was made. Because the hard part wasn't turning down the offer. It wasn't even dealing with the outcome of an unpopular choice per se -- hard to imagine these people thought "acquired by Yahoo" was the road to product success, even back then. It was dealing with the outcome of telling people they'd have to wait, possibly forever, to see their efforts rewarded (it took them 6 more years to IPO, with Zuckerberg famously devaluing the stock of early contributors along the way).

Noticing the lack of trust (possibly in both directions) _is_ a dark time, but it's hard to come to that conclusion when these things are referenced so obliquely ('people left' isn't a dark time, it's business).