It IS possible for them to be separate
I think the sociological and common definitions of homophobia are getting mixed up here and elsewhere in the thread. Eich probably doesn't fear gay people (common definition), but his support of the anti-equality campaign contributed to a society where homophobia has serious and sometimes fatal consequences (sociological definition).
he obviously fears the fact that gay people could marry like he can,or he would not have donated 1000$ against gay marriage.
You're taking a stereotype and applying it to an individual based on one point of data. It should be obvious to you that this is not going to be accurate and that it's logically flawed.
The fact that you find his politics regressive and consider him to be a bad person doesn't excuse your poor logic.
Eich has a known track record as a staunch libertarian, so it is quite possible that he believes government's involvement in marriage should be entirely eliminated. Of course, if this is what he believes, funding Prop 8 is a pretty terrible way to go about it, so it's still not defensible. I just want to call out the logical error being perpetuated here: They are separate thoughts and viewpoints, even if one tends to be rooted in the other, and they have equivalent consequences.