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In this case, the other information is 1) proven credentials in the subject matter and 2) general acceptance of his theories by a community with more credentials. He lacks the former and the latter, so I'm disinclined to give his theories much attention.
Plenty of so-called outsiders have made amazing discoveries before, or at least hypothesized what would eventually be an amazing discovery. Maybe that's the case here. Yet skepticism seems warranted without that being considered an ad hominem attack.
But like contravariant said, that doesn't mean the argument is wrong—just that it's a weak argument.
Really a fallacy represents a particular weak argument. The way to defeat them is not to name the correct fallacy but to point out the weakness.
If that doesn't work then you likely have the wrong fallacy, or the argument isn't fallacious to begin with.
Astrophysics is not a matter of personal opinion. It requires a lot of detailed knowledge and careful practice. Legitimate authority is relevant.
I am no expert but that wacky idea can be ruled out with concepts in an introductory physics textbook just based on the fact that the cosmic microwave background is a few Kelvin blackbody spectrum whereas the ocean temperature is 273K or higher (which would have a very different "warmer" spectrum).