My guess is they're hiding his identity because whoever he is meant to be a shock, and is also meant to mislead people into assuming it's Hal.
I don't know if the conflict is meant to be "Humans vs. Aliens" necessarily, so seeking aid from another alien wouldn't be a problem. The issue with the House of El seems to be their unjust imprisonment of metahumans, but maybe subsequent issues will make it good ol' fashioned xenophobia against aliens.
I dunno. That last issue leaned too hard on the "everyone is assholes" style of storytelling for my tastes, so I likely won't be around long enough to find out. Hopefully, the next issue is an improvement, because I love the art and setting.