You are failing to distinguish between the law as it's written and the law as it's currently enforced, and inventing a quasi-legal framework with no relationship to actual American law to justify your conflation. It's true that judges will sometimes consider legislative intent when the text is unclear; but in this case, the text is perfectly clear, so that's not relevant.

Large companies, small companies that want to get bought by large companies, and other conservative entities generally aim to comply with the law as written, even though there's lots beyond that you can probably get away with. Everyone should judge for themselves how far they want to push from clearly legal actions to grey to clearly illegal but unenforced; but they should know which one they're doing, and your advice isn't helping.

If we submitted a KDB inquiry asking the FCC whether the board in question required certification, what do you think they'd say? (It's free, and you typically get a quite competent response within a few days. If anyone wants to try, please use a generic description, and not a link to the particular product. I doubt the FCC would waste their time enforcing, but the chance isn't zero and the developers don't need that attention.) Or why do you think the Pi developers got certs?