Strict rules for tagging would just run into the same problems as strict rules for demonetization. LGBT groups won't be any happier to see their content publicly branded "sexually explicit" than just demonetized.
Penis/vagina -> nudity (even if it's medical or educational).
"Fuck" -> cursing (even if it's about the etymology of the word).
Advocating murder of group X -> ban (even if you're quoting a religious text).
If these rules are strict and clear, we have a chance of creating a legal-like system. Otherwise it's subjective chaos with everyone pissed off.
It's impossible to create an "objective" standard. Because what you want to rate is meaning, and meaning is subjective, based on context and intent.
One of history's most famous photos is of a fully nude girl, maybe 8 or 9 years old. It makes no sense to stick any labels to such an image without considering the context it was created in, and the cultural significance it has.
I'd also posit that it's impossible to define a clear distinction between a "lecture quoting a text advocating murder" and actually advocating murder.
Just as it is impossible to just say penis->nudity, without losing the vast difference in meaning and effect from a photo of Michelangelo's David to hardcore pornography.
That's because, fundamentally, there just is no such clear delineation. Give me any two photos including a penis, and I'll give you one that is more offensive than one, yet less offensive than the other.
The tech community loves to ignore the long history of these problems, and denigrates everything that can't be expressed as a smart contract as "biased" or "subjective".
But that's ok... In less than 200 years we'll have a great algorithm who will finally render the definitive test of what's porn and what's art: "I'll know it when I see it".
A steel-manning of context should be enough to draw a distinction. Sadly, most contexts today are being redefined by folks who are seeking or making porn for those who need to get off on their own moral outrage.
"And he that blasphemeth the name of the LORD, he shall surely be put to death, and all the congregation shall certainly stone him."
"If a damsel that is a virgin be betrothed unto an husband, and a man find her in the city, and lie with her; Then ye shall bring them both out unto the gate of that city, and ye shall stone them with stones that they die"
An alarming number of social justice advocates have been equating words with violence. Canadian Bill C-16 (now law) is particularly troubling because under the Ontario Human Rights Code it makes debate over gender neutral pronouns a punishable offense. It seems to me that the folks at YouTube are, necessarily, responding with the most "conservative" policies to avoid "controversy" (i.e. boycotts).
I would say that this should not be banned. Let all who profess these beliefs be out there in the open so that they are easier to find.
Could you give a specific example of what you meant?
The classic example I can think of, that has already generated headlines, concerns nudity policies in social media (Facebook in particular) that have flagged breastfeeding mothers for "nudity" (and thus ticked people off). A "by the letter" policy risks much more of this sort of thing... flagging something as "bad" that much of the social norm says isn't really a big deal.
One other thing I would worry about with "objective" rules is what culture determines the "watch list". The cultural norms for what is taboo actually does vary to some degree from culture to culture. Youtube is used heavily in so many countries, with diverse cultures. How can a single policy encompass the social norms of countries as diverse as, say, heavy Youtube using countries such as India, Japan, the UK, Germany, and the US? (And this isn't even accounting for the diversity of culture within these countries.)
As an example, the swastika, which is extremely taboo in Germany and triggers "hate speech" flags in much of the rest of the West, is (usually styled differently but still) a religious symbol in India. You could create a generic flag category for "swastika", but chances are this will eventually flag some, say, Hindu content from India and tick those people off.
I suppose you could structure the rules to account for as many cultural norms as possible, but that can get very complicated fast.