Actually, there is no need for the code in functions_bigthree.php in MEMBERINFO. There is probably some already existing value in the others to check too.
MEMBERINFO
use the existing info in $userinfo['action'] like this
PHP Code:
<if condition="$show['avatar']">
<td><img src="$userinfo[avatarurl]" alt="<phrase 1="$userinfo[username]">$vbphrase[xs_avatar]</phrase>" border="0" style="border:1px solid $stylevar[tborder_bgcolor]; border-top:none<if condition="$userinfo['action'] == false">;filter:alpha(opacity=40);-moz-opacity:0.4;opacity: 0.4;</if>" /></td>
<else />
<td> </td>
</if>