It's reasonable to conclude that some people cannot consent to some things, particularly things they don't understand. Sex with children, animals, and adults under some kinds of intoxication fall into this category.

Sex in public can work, if that public consents. Indeed there are some publics that do consent, usually small communities, but it does happen.

Consumption of human flesh is theoretically A-OK, it's the obtaining of that flesh that is difficult. The dealing of human material outside of controlled channels can lead to the killing of people for money or power, which is why it's illegal to buy or sell organs for transplants or research. With stakes this high, any compensation can be twisted into coercion. This, plus the risk of bioaccumulation and parasites, has led the consumption of human flesh to be a taboo, although exceptions do get made in extreme circumstances. As such, if the origin of such flesh can be confirmed to be uncoerced and not used for long-term sustenence, and this can be rigorously enforced, then I have no problem with it.

The allowing of things which may lead to disallowed things does depend on the ability of a community to understand the risks and adapt to reduce them. For example, Canada recently began practicing medically assisted dying for those who choose it, yet some doctors have already been criticised for pushing it unprompted instead of recommending treatment. I shudder to think what could happen if insurance companies could legally consider it a valid alternative.

The issue here is that some things can create an intolerance for some rights, without violating those rights to begin with. Where the line is drawn should depend on how strictly the line can be enforced, so while historically many lines were drawn very broadly, we have stronger social technology now, and we can free up areas near those lines. Should we spend the effort to have those thinner lines is another question, and usually depends on how useful that area is; for example stem cell testing could teach us a lot, but eating human flesh is very inefficient and possibly dangerous long-term.

If something causes intolerance, then we certainly should create laws against that intolerance. It's usually simple to make the laws against the thing itself, but laws could be made that allow more things without allowing the intolerance. It can be a complicated matter, but one worth pursuing, otherwise everything would eventually end up outlawed.