As a bisexual-leaning-gay man, I have some strong feelings regarding people holding outdated views. VERY strong.
In the end balance, though, Mr. Eich's donation was... fairly small, relatively speaking. This cost is likely MUCH smaller than the potential damage this could do to Firefox and the various freedom-centered movements that depend on it.
Therefor, this is a mater of PICKING YOUR BATTLES and realizing that those who normally would be seen as an enemy can sometimes become an ally against a larger foe. Winning difficult social issues such as marriage equality would be a LOT harder without tools like firefox to maintain free (as in speech) communication on the net.
/* especially when certain intelligence agencies have been found using this kind of wedge issue to break up groups they perceive as a threat */