[lsc]

https://www.law.cornell.edu/uscode/text/17/407

"Neither the deposit requirements of this subsection nor the acquisition provisions of subsection (e) are conditions of copyright protection."

Which is to say, of course, that you are right, however you don't lose copyright protection if you don't comply. - it looks like there are no penalties until they ask you for a copy.

This lines up with my understanding that if you are serious business, the LOC gets a copy. If not? it doesn't really matter, and if you become a big deal later, well, following the rules helps you establish provenance, but isn't required for protection.