Should religious groups who give aid to people after natural disasters be allowed to promote their religion?

Don’t misunderstand me here, I’m not saying religious groups should be banned from giving aid to people, but don’t you see something really unethical in these religious groups using the opportunity to promote their religion? Take those slimy Mormons for example; this is a very wealthy religious organization and they seem to wait with gleeful anticipation for natural disasters just like the recent one in Haiti so they can go there and put on a public display of how charitable Mormons are. And you can safely bet the Mormon aid workers wear T-shirts and hats and other labels like this promoting their ridiculous religion which is based on the lies of renowned fraudster and is run more like a sinister cult than a religion. Am I being too cynical here or does anyone else see this as severely unethical exploitation that should immediately be stopped?