Sure, if my senior developer had something horrible happen to him, I should allow him to work 0-2 hour weeks, keep him in the same position and payroll, and let my startup go down and hurt the lives of the other 9 employees who worked hard on it.

"Respect and care" means among other things, that you keep your business running so it can respect and care for the majority of employees. If you're going to take things to extreme, why then I need to "respect" every candidate by hiring, and "care" for any employee who just feels like taking a 20-month meditation trip to Tibet, since the woes of this modern world are depressing him.

The fact remains the same: a lean, highly leveraged startup can't allow developers to go off on vacations for 3-6+ months, no matter how badly they need it. Hell, if you're that kind of startup, those 3-6 months may very well be your entire product (or life!) cycle.

If your senior developer has something horrible happen to him* , and you then immediately cut him loose because he's of no use to you any more, what happens to your product? You're a startup, so you're unlikely to have huge amounts of redundancy to cover for them when they refuse to train their replacement or answer support questions about your complicated 6 month time-critical project from their dying, dysentery-stricken family members' bedside.

Also, taking that sort of hard-nosed attitude will make the other developers on your team more wary, which will result in higher salaries, more turnover and (if you're a real idiot) no new staff, since word gets around. Ultimately you depend on your staff, so if you play hardball you're likely to reap the 'benefits' further down the track when you need them.

* - this was your original point, not some "meditation trip to Tibet"

If you're a startup and someone needs a 6-month vacation for mental health reasons, you need to cut him loose. If he's done good work and is willing to leave in a way that minimizes damage to the company, try to leave the door open and give him a good reference. You're right, of course, that startups cannot afford to have important people become nonproductive.