Everyone needs to get over themselves. Measuring society based on small groups who are "offended" will send us into a deadlock of boredom. In fact, it smacks of tyranny.
The father has a right to be upset only if his son, or his son's death (which is understandably tragic), is directly involved with the attraction, which it is not. He does NOT have a right to imply that the attraction offends unless his SON was the primary target of it, and his son was not. The best he can come up with is that his son's affliction is remotely connected to the conditions expressed (and exaggerated, that's what entertainment does, exaggerate) in the attraction.
I'm sure most people would find mental treatment rather boring, because it is.
Grow up, grow out, and stop being and/or capitulating to the emotionally handicapped snowflakes of society.
They have rights, but there is no right not to be offended, and there should never be, because they CHOOSE their offense. No matter what you do, someone, somewhere, will find some reason to be offended. It's time to stop giving these people platforms.
Being "offended" does not immediately grant someone the ethical, nor the logical, superiority in any situation. It just means they find it offensive, and that is their problem to get over, not society's.
If society en large finds it offensive, than they will not attend, and the free market will be influenced by reality. But attempting to sway and shame society into not consuming something which they are interested in consuming, simply because you've decided you find it offensive for whatever reason, is just...sad...
I am getting really tired of these trends.