Your link above appears to be about SharePoint List forms. I have InfoPath 2013 on my machine. I just opened and edited a SharePoint list form for a 2010 SharePoint site. I had no issues. For a standard browser form, you'll need to make sure you set the form's compatibility level to InfoPath 2010, which the user in the last post in the linked thread appears to not have done.
Hilary Stoupa
