I would suggest looking for another plugin because he is wrong -
his plugin is causing the issue
To prove it do the following
1) disable the plugin
2) go to ato->Style & configure COMMENTS->Comments Are Closed text and enter
HTML Code:
<p>atahualpa says comments are closed</p>
3) go to a post and in the 'discussion' section' check off the 'Allow comments.'
4) in the front end go visit the post - you will see
HTML Code:
atahualpa says comments are closed
5) now activate the plugin and go visit the post again and you will see the
HTML Code:
Comments are closed
it comes from line 60 of your 'class-comment-form.php'
<p class="nocomments">Comments are closed.</p>
I personally also have an issue with any free plugin that requires me to register - this means they are 'checking in' each time it is used and I always have to wonder what are they collecting...
also any plugin or theme author that won't spend the time to 'consider' thier product may have an error is someonw I choose to stay away from.