Honestly it's not just "in heat" that make up is simulating. It's the general sympathetic nervous system which is used in any aroused situation such as running from a pack of lions, or any sort of physical activity or fight/flight situation.
Which is irrelevant because make-up and other vanity products are not created to simulate fear; likewise the effects of fear on the body produce different physical reactions even in something as small as facial structure changes than being horny does. The effects of fear and fuck should not be equivocated because they use the same system, nor should the effects make-up and other vanity products are intended to simulate.
Yes, a character made to be in your face is often better off with Greaves and the such, but that's why this is a skin (and one of many Shyv skins).
It's not merely that it is inconsistent with the idea of the champion itself. That's not even part of the discussion; skins aren't necessarily required to be consistent with the concepts present within the basal form of the champions themselves.
Skins are however required to be consistent with the concepts present within the skin. This is referred to as "internal consistency."
Now consider an up-armored skin where the idea is very clearly getting in your face an aggressively beating you into the ground. Now add high heels, a form of footwear which is known only for making the wearer look sexy and providing and unstable platform for mobility. Congratulations, the skin becomes a good example of internal inconsistency.
Sona is never gonna dress for death metal music...
In Universe, she did. Pentakill was a band which existed within the canon of the LoL Universe, the first two members of which were Mordekaiser and Sona. Technically speaking, it's not even inconsistent with Sona, as the Psychology which drives Metal Heads and Classical fans is identical. Of course none of this would be known if one had not read the JoJ.
It's also irrelevant to the larger point. A skin being inconsistent with the champion does not make up for the skin being inconsistent with itself. In the case it goes even further, the Victory concept is consistent (in theory) with the concepts presented within the character's basal form. As result, the heels just end up providing inconsistency with both.
In Shyvana's classic skin I think it's very important to stick true to her character, after she's won her fight and become 'champion' Shyvana why can't she go crazy and wear something else?
Warriors rarely do anything for no reason. They are even less likely to do something for no reason when what is being done could hamper their combat effectiveness, as heels necessarily would. Pragmatism is a warrior's go to rule set. One might wear heels in a dress during a social function (assuming they aren't on guard duty, or are BUT are required to blend in with the crowd), but one would never do so in a direct, violent confrontation.
Victory Shyvana does not strike me as a dress up skin for a social function. It also does not strike me as a mish mash skin for the hell of it. So there isn't an excuse for the internal thematic inconsistency.
If there's a situation where she wants to put on a pair of heels whats wrong with her having heels and what does being 'badass' automatically mean the woman can never wear a pair of heels in her life?
Being badass and appearing badass are two different concepts. This skin is as of now, neither. Incidentally, "being" badass is a matter of function, where as "appearing" badass is a matter of form. When measured in these contexts, heels will never be badass regardless of how they make one appear, simply by virtue of being an article of style rather than substance.