As I understand this question, unless we and the aliens have some common or coincidentally similar DNA, assuming aliens have DNA, we would not serve as a food source.
Since the odds of contact appear to be quite low, and since the odds of catastrophic results from any potential contact appear to be even lower, and since the odds of direct contact are astronomically low, and since the benefits from even radio contact with another civilization could be enormous, say for example if they sent us their knowledgebase, I tend to think the potential benefits vastly outweigh the potential risks.
Next, if ET is out there and can get here, that is assuming a level of technology perhaps a million years more advanced than ours, and considering that even we are imagining ways to discern regions of space, solar systems, and even planets that could support life, it seems reasonable to assume that in any event, we can't hide. If ET could be and desires to be a threat, he likely already is; which means we should all be dead or ETís slaves by now.
Go for it!