Upvote:3
There is no such regulation. Visa for the US are for the US, not for Houston or Cornfield, Iowa, or whatever.
Many countries donβt even have direct flights to Houston, so even if you book a connection, you will land somewhere else, go through immigration, and then take a domestic connection (where there is no immigration, and nobody cares about visa status).
Note though that the visa is not an automatic entry; the visa holder will still be questioned by immigration officers, and if they think something is conspicuous, they can deny entry. It is important to be able to present a clear and convincing planning of what you plan to do, how you can afford it, and when you will leave. But it doesnβt matter what the original planned city was.