This is so completely wrong I don't even know where to start.
First: even if this were right, it's totally irrelevant. The government can't violate the constitution through its regulations, either. The government can't, for instance, pass a regulation saying that no blacks can be hired at federally regulated airports. Nor could it forbid people from saying bad things about President Bush on an airline.
Of course (persistent error #1 in above analysis), constitutional rights are rarely absolutes -- they can be violated if there's a compelling governmental interest. Hence, I don't have the right to falsely yell fire in a crowded theater. And you don't have the right to pretend to hijack a plane for fun.
Despite this constitutional requirement, federal mandates can discriminate against people (error #2). This is because there is nothing in the constitution that outlaws discrimination. What the constitution says (or at least, how it has been interpreted) is that the federal government can't discriminate against people who are members of a protected class unless they're protecting a compelling government interest. Gun ownership is not a protected class; they only need some rational reason to discriminate against you.
While I'm at it, I'll clear up the commerce clause/gun thing for you:
The federal government is a government of enumerated powers. That means, Congress can only pass laws that are on a particular list in the Constitution, and the Supreme Court will overturn federal rules as outside the power of the government if they don't flow from one of the items on the list. There is no power that says "you can regulate guns" but there is a power that says they can regulate commerce, and arguably, the movement of guns and people is commerce.
However, the presence of something on the list of enumerated powers doesn't mean that they can automatically do it. For instance, interstate commerce would be effected if I said very bad things about beef; the government cannot forbid negative speech about beef. So the Bill of Rights says, "even if you have the enumerated power to do something, you may not do it if it violates one of these rights."
So, in order to be constitutional, federal gun control legislation must both fall under an enumerated power and not violate the constitution. Commerce clause explains the first; the second, of course, stems from the fact that (a) the second amendment has been emasculated, and (b) remember, constitutional rights aren't absolutes, and so security issues may trump the second amendment.
Some regulations have only civil penalties, as you point out. But others have criminal penalties, as you will discover if you try to bring a gun onto a plane. See here for instance.
Furthermore, it's horribly wrong to analogize to OSHA -- OSHA is part of a whole scheme of workman's compensation, which preempts a whole bunch of civil claims. In the case of OSHA, the regulations are tightly linked to liability.
But not all regulations preempt civil suits. Note that people who had loved ones die in 9/11 still sued airlines who had complied with FAA regulations of that time. It is often true that someone who violates a regulation opens themselves up to liability. The inverse -- that following the regulation saves you from liability -- is often false.
Take, for instance, drugs that get FDA approval. Fine, according to regulation, but drug manufacturers get sued all the time.