The government can regulate any business. It's in the Constitution. The government is not supposed to regulate speech. That's also in the Constitution. Private companies, on the other hand, are not required to provide a free speech platform as part of their products/services.
Where, exactly, is it in the US Constitution that the government can regulate
any business?
I can see Commerce among the States in Article I, Section 8, but what about a business that doesn't do anything across state lines. Among being the operative word, meaning member or members of a larger set. The operative word would be "within" if it mean to regulate in a single state.
To me, I read the US Constitution how it stands, and not some cockamamie case of a person growing food to feed my livestock in Ohio affects the price of feed in the other states because I'm not buying it, therefore what I do on my farm is Interstate Commerce, so that can be regulated. (Wickard v. Filburn, 1942) uhhh.... what?
Speaking of that, the government does regulate firearms, and that is explicitly prohibited in the 2nd Amendment. No other part of the US Constitution says, "shall not be infringed," yet infringing goes on all over the place "for the children..." (gotta be 18/21, magazine sizes, can't saw off the end of a shotgun, background checks, blah blah blah, some of which I do agree with, but just because I agree with something doesn't mean it passes Constitutional restrictions on the government imposing them.)