That is the problem with this law, the vagueness.
You claimed that there is something in the law that puts a person in jeopardy for selling a gun to a friend. That's not a complaint that the law is vague, that's a specific claim.
Please quote the portion of the law that indicates that a single sale of a privately owned firearm to a friend makes a person subject to arrest. The law includes the terms 'repetitive' and 'repetitively' which makes it very difficult to interpret it as referring to a single sale.
If that weren't enough, it also specifically states that a single sale, in the absence of other evidence would not qualify as dealing in firearms.
According to Garland, you are less likely to be prosecuted for selling twice in five years that if than if you do so "several times over a short period", but he does not rule out a life altering prosecution over it.
To be fair, that's an example taken from an explanation that the term 'repetitively' should be taken to have its ordinary meaning as opposed to a specifically provided legal definition. He could have just as easily said: "The longer the interval and the fewer the sales, the less likely the behavior is to be interpreted as repetitive." The meaning would be the same.
Furthermore, the repetitive nature of the sales is neither the primary nor the sole criterion for determining if a person is dealing in firearms, so it's inaccurate to make it seem like taking "predominately for livelihood" from the law makes 'repetitive/repetitively' the only remaining criterion.
Look, I'm not in favor of the new law, but I don't think that you're doing anyone any favors by taking a casual example from one explanation in the 80 something pages comment section and making it seem like it is not only part of the law but is providing the sole criterion for prosecution under the new law. I think it would be a lot more helpful to talk about what the law does say and how it says it. If you are honest about it, you will have to admit that 2 sales in 5 years is not going to put a person in jeopardy of prosecution in the absence of other evidence.
Ok, folks. I'm going to, once again, strongly suggest that people who find this topic of interest, should read the actual rule for themselves. It is not difficult to understand, and there are pages and pages of explanatory text for those who do need a bit of help.