I'm not sure of the Federal governments legal standing to do this they must protect from race, gender, disability, age and other clear factors of difference under the Constitution.
What? Show me where in the constitution you find this. The constitution protects the rights to vote on the basis of race and gender. Not protection from general discrimination on any other lever or for other reasons.
As far as discrimination in business matters, I refer you to the Americans with Disabilities Act, The Civil Rights Act of 1964 (Title VII), and various Supreme Court rulings. NONE of which are defined in the constitution, but by congressional Acts or Court rulings.
And by the way, it IS perfectly legal to discriminate against any class not clearly defined in those laws/rulings. Hence I could discriminate against smoker (smoking is not a protected class), people with more than 7 freckles, motorcycle riders, etc.
And lastly, Congress has the right to pass laws that affect even local business under the Interstate Commerce clause of the constitution because government lawyers have proven to the Supreme Court again and again that even an organization that does NO business out of state has interstate commerce ramifications. I suppose if you could prove that EVERY aspect of your business was local, you might have a leg to stand on (all my paper supplies are local, I make my own pens, etc etc), but I doubt it.
Anywho, I'm still undecided on the trangender part of the law, I don't like discrimination in the workplace, but I can see how in certain industries, it might make more traditional (old heads, etc) customers uncomfortable.