accessibility issue

i think there is an accessibility issue with this plugin
especially with wcag 2.0 Success Criterion 2.1.1
http://www.w3.org/WAI/WCAG20/quickref/#keyboard-operation

users can’t navigate and use the buttons with keyboard
primarily for official sites accessibility is a core request

maybe a solution would be to change the container html from <span> to <a> eg here:

<span class="switch off">nicht mit Twitter verbunden</span>
<span class="twitter_dummy twoclick-network"> </span>

http://ww.wp.xz.cn/extend/plugins/2-click-socialmedia-buttons/