Probably because it's simple enough just to make your own bbcode from the twitter embed code.
Title: Tweet
BB Code Tag Name: tweet
Replacement:
Code:
<script type="text/javascript">
function loadx(data) {
document.write(data.html);
}
</script>
<script type="text/javascript" src="https://api.twitter.com/1/statuses/oembed.json?id={param}&callback=loadx"></script>
<div class="twitter" onLoad="loadx().html"/>
Example:[tweet]429641515728527360[/tweet]
Description: use the last number bit from the end of a tweet url and put between tweet tags.
[tweet]429641515728527360[/tweet]
Use {option}: no
Remove Tag If Empty: Yes
Disable BB Code Within This BB Code: Yes
Disable Smilies Within This BB Code: Yes
Disable Word Wrapping Within This BB Code: Yes
Disable Automatic Link Parsing Within This BB Code: Yes
You do need to refresh the page before it shows after posting, but that's no biggie.