Your supervisor is key. You have to like them, because they’ll be criticising your work for the next 3-4 years.
This sentence resonates with me particularly. I was encouraged to choose my PhD based on love of topic rather than supervisor. I had multiple topics I enjoyed, but ended up going with a worse supervisor and a topic I thought more interesting than a better supervisor and a slightly less enthralling topic.
After a year, I quit my program.
What I learnt: even though a topic might be slightly less interesting, the people you work with (and in particular, your supervisor) can make you love something more.
(NB: Obviously I wouldn't recommend choosing a topic you have no interest in and/or hate just because you get along with the supervisor!)
(Obviously, this instance can be taken solely as a political issue - donating to a political campaign. However, I think the underlying human rights issue is still there. This is an assumption. Mr Eich could have donated for purely political reasons... but I find that difficult to comprehend.)
I understand where you're coming from with point 2. It can be very damaging for a company. Firing people because they're a Democrat or a Republican (or forcing all your employees to vote for Romney or Santorum) is going to get you in trouble, and quickly.
However, I believe the split here comes whether this is a "political issue" or a "human rights issue". In my opinion, it's human rights. And I believe any company should ensure that its employees are not fighting against equality. I guess this also ties into equality for its employees. I assume there are LGBT employees of Mozilla, and I think they must feel pretty uncomfortable right now.
Unfortunately (again, in my opinion, etc.), it's treated as a political standpoint, something that big parties can argue about. But it isn't - it's about whether LGBT individuals have the same rights as straight people.
http://www.wired.com/design/2013/11/hockney/