It's not a loophole. A loophole is when you have some case or situation not covered by the rules allowing someone to get away with something that the rules were not meant to allow.

E.g., a company arranging for its shareholders to be able to report dividends as capital gains rather than ordinary income by doing a fractional stock split followed by a mandatory buyback instead of declaring a dividend, with the split/buyback designed so that each shareholder ends up with exactly the same percentage ownership they had before and with cash equal to the exact amount that would have been otherwise distributed as a dividend [1], that's a loophole.

An author picking an open source license that specifically and intentionally allows anyone to use their software and make money from it without having to give the author anything is not a loophole.

[1] Yes, this actually happened around 100 years ago. The rules on buybacks were changed to fix it. But them some legitimate cases of buybacks that should have been capital gains became ordinary income, so more fixes were needed. The result is that what once needed at most a line in the tax code, if it even needed mention at all, became several paragraphs. This is why we do not have a small, simple tax code--there is a massive incentive for people to find even the tiniest loophole and exploit it, and so you end up with multiple paragraphs for things you at first would think could be done in a sentence. (And don't say a flat tax would help...almost all of the complexity in the tax code is in determining what gets taxes, not how much the tax is once you have figured out the what).

All of my enduring open source contributions have been made while employed by a big(ish) company. I went through the effort to get them upstreamed so other people wouldn't have to make the same effort to debug and fix the same issues. Does that enable other companies to avoid hiring engineers to do the same work? Maybe, but it also enables everyone to benefit from things working just a bit better.

I don't need a royalty from my fixes, I was compensated for my time. I don't even care about a credit, but I understand some do.