Sightstone and not Ruby Sightstone should be core. You don't even mention Trinkets and the Trinket swap after Sightstone purchase in the cheat sheet. Sunfire Aegis is a rather selfish purchase not focusing on the support role, Randuin's Omen is superior to it.
Quintessences are either 3 of the same kind or 2/1, nothing else.

While I do not agree with a bit of information in your guide, such as Frozen Heart being core vs a team that is mostly AD, I do frequently play Shen as a support in high ELO, so I can verify it is very much a thing. In fact, I rate him as a B tier support, which is quite respectable. Regardless, your guide needs some more explaining. Also, it dosent exactly look good aesthetically, and although you would think that wouldn't matter that much, it really does, especially if someone chooses to read your guide over someone elses. I will withhold my vote until you do so, but it looks great so far, and I mostly agree with the information you are giving, and can verify it will work at most ELOs.

The things I am skeptical of:

27 points in defense is highly unnecessary, I normally use enough in utility to at least get the summoner spells cooldown, but to each his own.

The Frozen Heart issue previously mentioned.

The choice of Quintessences, it seems like you would want 3 of 1, not vice versa, but again, this is just an opinion and this is not a major flaw (or necessarily a flaw at all)as much as it is slightly confusing.

Mark of Scaling Health is one of the least optimal marks in the game, you are giving away mark spots you could use for armor instead for 80ish HP lategame (You can get rid of 80 hp with 1-2 auto attacks from a support).

However, these are just my opinions. If you expand your guide and explain your reasoning, and it makes sense , I will give you my support and my upvote.

Best of luck!