and carry. With a permit the law doesn't apply to you on public transportation. RTD posted the signs as a reiteration of state law, that it is a SPECIFIC crime to carry aboard public transportation - sorta makes people feel safe and fuzzy/warm.
The only places that can ban it are PRIVATE property owners and/or fixed buildings that have a screening process/metal detector that is staffed.
RTD is not a private entity. Costco can (and does) prohibit concealed carry, for instance.
I hope she carries a taser too, I'd hate to think how hard a sight picture would get on a moving bus! I'd also suggest finding an old IIa front vest panel to sew into the interior of whatever bag she is carrying. They're pretty lightweight and offer good protection at need.
There was discussion about this back when CCW became "shall issue" and the position of RTD was then, and is now, that a lawful permit carrier can ride armed. Is there a specific statement allowing it? No, they think if they dont post about it, then they cant be sued for it.