Anti-Splog Shortcode Breaks if wrapped in shortcode

I've encountered two scenarios now where WPMU Dev plugin shortcodes do not render if they reside inside another shortcode. I was able to work around one, but now I'm hoping someone can help me resolve the other.

I'm using the Global Content Blocks plugin to include a PHP statement in a widget (or on a page) via shortcode. The problem I've discovered, however is that neither the ust_wpsignup_url shortcode nor PHP snippet work when included in the code being rendered by the other plugins shortcode.

For instance, this code below:
<a title="Join Tripawds Now!" href="[ust_wpsignup_url]">
Returns this URL in the sidebar:
http://tripawds.net/news/ust_wpsignup_url

And this:
<a title="Join Tripawds Now!" href="ust_wpsignup_url()">
Renders this:
http://tripawds.net/news/ust_wpsignup_url()

For the GCB plugin to work, you must enter the PHP code without it's open (<?php) and close (?>:wink: tags. I have the conditional statement below working perfectly, except for the signup url. It welcomes logged in users by name with their avatar and links to their blogs. Users not logged in, see different content with a Join button that has the ust_signup link.

if ( is_user_logged_in() ) {
global $current_user;
get_currentuserinfo();
print '<p>Welcome Back, ' . $current_user->user_login . '!</p>';
print get_avatar( $current_user->ID, 96 );
print '<p><strong>Your Blogs:</strong><br />';
  $blogs = get_blogs_of_user( $current_user->id );
     if($blogs) {
     	 foreach ( $blogs as $blog ) {
         echo '<a href="http://' . $blog->domain . $blog->path .'">' .  $blog->blogname . '</a><br />';
	 }
print '» <a href="http://tripawds.com/forums/">Discussion Forums</a><br />';
print '» <a href="http://tripawds.com/chat/">Live Chat</a></p>';
     }
} else {
print '<p>Log in or register now to get the most benefit from this site.</p>';
print '[unordered_list style=tick]<ul>';
print '<li>Free Tripawds Blog</li>';
print '<li>Instant Forum Approval</li>';
print '<li>Live Chat and More!</li>';
print '[/unordered_list]</ul>';
print '<p> <a title="Join Tripawds Now!" href="[ust_wpsignup_url]"><img src="http://tripawds.net/wp-content/uploads/2008/01/btn104x42-join.png" alt="btn104x42-join" width="84" height="42" /></a> <a title="Log In and Return to Forums" href="http://tripawds.com/wp-login.php?redirect_to=http://tripawds.com/forums/"><img src="http://tripawds.net/wp-content/uploads/2008/01/btn104x42-login.png" alt="btn104x42-login" width="104" height="42" /></a></p>';
}

The site is currently hidden, so I've included a couple screenshots of the front-end results. You will notice the Woo shortcode for the list style renders fine, but the Anti-Splog link shortcode does not.

Could anyone provide some direction so I could get this working? After reviewing this related topic I'm thinking I may need to add the ust filter to my code above so it is immediately referenced, if that makes sense, but i'm not sure how. Any other suggestions are greatly appreciated.

Thanks in advance for any feedback!