You are very naive. Ask any pastor or church board. The concern with losing the tax exempt status for speaking the wrong thing is something they are all concerned about. That has been the case in every church I have attended (outside of my old small rural church I grew up in). I know of one that got into a dust up in preaching an anti abortion sermon. Seems that the pro aborts saw it as an endorsement of a certain candidate, and reacted to it with a complaint.
We apparently attend very different types of churches. I'm a deacon in my (evangelical Christian) church and my pastor and the church Elders would rather revert to holding church services in private homes - as the First century church did - and give up the nice building and some effective programs than submit the church to the whims of the secular state government. We are willing to submit to government authority in matters not germane to salvation but homosexual behavior is clearly a sin and cannot be condoned by the church recognizing 'gay marriage', even if the government legalizes the practice. If that threatens the church's tax-exempt status, so be it. We do not intend to sell our bible-based beliefs for a tax exemption from the state. I submit that those who assume the majority of churches (of all faiths) would do so are naive - and mistaken. However, I trust it will never come to that, but these days, I'm not as optimistic as I once was.