Let me do the work for you; since you'd rather just spread FUD then look for facts.
It also sounds like they are trying to fill a part-time role. "Must be able to commit to spending 80 hours or more a month" = ~20 hours a week, but given the ebb and flow of release/bug/patch work needed...
FUD
I don't know if there's really a better way to manage this need. They need a pretty niche specialized developer, so you have to cast a pretty wide net (globally, mind you) for remote work.
Yes, people should know what they are getting into, with independent contractor work. I just think there is (probably) some nuance to this particular case; where hiring people on as an employee doesn't make a lot of sense.
Find the skills gaps that you have; find the thing that interests you about it; and dig into that fundamental piece, don't understand what the fundamentals might be, go check out .edu, or certification outlines with the vocabulary/knowledge you do have so you can build from the concepts (and benefit from their already determined progressions) , so you can developed additional vocabulary and knowledge of the discipline.
I think the gatekeeping part isn't the warning or cautionary advice being given, It's the failure to point, and give direction to, the relevant thing(s), the skill sets, the place to start in order to understand the complexities.
Like the hart-surgeon analogy given elsewhere in the comments; it's not just the dire warning of 'you can kill someone' - it's the humanity to say, well if you want to learn how to do this, you're going to have to start by having an understanding of basic biology, organic chemistry, human anatomy, etc, and to learn about those things go here...
I think you've missed the point OP is trying to communicate. It's not that these things aren't relevant, highly important, and good caution/warning. It's the gate that people are creating with these no depth explainers. "you need to understand" "if you don't know" -- then fail to provide direction to people who want to know, to learn these things, to figure out where to start; that's the gate.
It isn't criticism if it isn't based on fact. The U in FUD stands for Uncertainty; and what do you think "might" falls under, or it's relation to sowing Doubt?
The law related to job postings, is a labor law, that also covers minimum wage, and uses the same definitions. Labor Code Section 432.3 (Pay Transparency Law) Labor Code Section 1197.5 - California Equal Pay Act (Fair Pay Act) Labor Code Section 2750.3 (Employee vs Independent Contractor Classification)