How to prevent iOS from styling an emoji?

Look at these characters: 💬💬︎🌄🌄︎

Depending on your device, they'll look like this (a Windows screenshot of a Facebook comment):

Notice how the 2nd and 4th emojis are flat rather than stylized*. It's because I inserted an invisible U+FE0E character after each to tell devices not to change the appearance of the character.

However, on the Facebook iOS app, they look like this:

It seems that iOS isn't honoring the Variation Selector-15 (U+FE0E) character and stylizes all of the emoji characters.

How can I force emojis to appear as the basic flat text version?

_{* P.S. As a side note, when I inspected the HTML on Windows, this is what I saw, which I guess is how Facebook's website replaces the emojis with their own images whenever U+FE0E isn't present:}

<span class="_3l3x">
<span>
<span class="_5mfr">
<span class="_6qdm" style="height: 16px; width: 16px; font-size: 16px; background-image: url(&quot;https://static.xx.fbcdn.net/images/emoji.php/v9/t6e/1/16/1f4ac.png&quot;);">💬</span>
</span>
<span class="_4ay8 _3kkw">💬︎</span>  
<span class="_5mfr">
<span class="_6qdm" style="height: 16px; width: 16px; font-size: 16px; background-image: url(&quot;https://static.xx.fbcdn.net/images/emoji.php/v9/tf/1/16/1f304.png&quot;);">🌄</span>
</span> 
<span class="_4ay8 _3kkw">🌄︎</span>
</span>
</span>

I think the problem is that iOS uses the Apple Color Emoji font for everything, and this font does not yet honor the mechanism for making characters text format. The only way to get around that is to use css or similar means to force iOS to use a different font which only has text versions.