"Assuming your story is true, you are an extrasolar intelligence and Mars would like to eventually establish diplomatic relations with your home planet if we're able to contact them. If you decide to run off and do some piracy I suppose we'd stop you the same as any other pirate, but I really don't think that's an operative concern unless you're in fact planning to go do some piracy. As far as what others will assume, you look like a human, specifically a human from Earth, and if you claim otherwise they'll most likely just think you're insane, at least until we can offer the world some verifiable proof otherwise."
"Uh, as far as those other regulations you were asking about—first of all, you're not MCRN personnel and aren't obligated to do anything; second, none of these things are actually known to exist, it's just types of thing we've theorized about. Things that—would more likely than not destroy humanity if left unchecked." Come to think of it, it's pretty arguable that the situation where this man, even if he is actually human, is given incomprehensible powers by his 'god', triggers some of these conditions. He seems fine, but 'don't fuck around with alien superintelligences' is not a rule you make exceptions to because things seem fine.
(He doesn't say this part out loud.)
"You're not legally a prisoner, but you are obliged to obey my orders while on board this ship and as a practical matter cannot very well leave it. I suppose if you have magic for doing so I wouldn't stop you."