fyi applying the following code:
/* To hide the date and comments */:
.wysijap .postmeta { display:none }
to 2011 child style.css doesnt remove "This entry was posted by XXXXXX. Bookmark the permalink.", "Logged in as XXXXXX. Log out?", "Leave a Reply" or "Post Comment" field.
Also, the alternate method suggested on the page link you provided of creating a single-wysijap.php file in the child theme folder, copy/paste page.php content and then editing or just saving (because there is no auther defined) didnt change anything either.
Any suggestions?