Not all agency standards prohibit free ascent training. In the case of advanced programs, it's often not mentioned at all. As long as the minimums are met, training agencies are content. Some however might denounce this type of training because of the dangers involved.
Personally, I believe in the application of common sense as the largest indicator of my actions. If I am certifying a diver to dive to a depth of 130 feet, it seems only reasonable to me that some effort must be made on my part to teach him to get to the surface unassisted if required. As we've also mentioned, free ascent isn't necessarily the best first option, but I believe it's valuable for a diver to have it in his "bag of tricks," if he finds himself out of other options.
It's also worth mentioning that an instructor is liable for all acts or omissions. In other words, it's not only what he does that can get him into trouble, but also what he fails to do that he is responsible for. I would much rather that an Agency abandon me, if my argument in court was a reasonable one, rather than an Agency supporting me and the judge ruling my actions were unreasonable.
Liability is all about establishing what is reasonable, given the instructors diving experience and established knowledge. If this is considered to be relatively high, it can bite you on the butt. You may be held to a higher standard of care, because you should know better. The standard-of-care in medicine is different between a family physician and a specialist, for example. The more training and experience, the higher the standard.