The lady who wrote the article did a follow up in the comment section where she acknowledged that the rule had changed back to two spaces.
"Well, here’s a new wrinkle: One of my facebook readers pointed out the although APA guidelines at one time reduced the required spacing after a period from two down to one,
they returned it to two in 2009 in the 6th Edition (see section 4, first bullet)."
Perhaps she should have just removed her posting.
Now, here's how it works on computers. If you type something and leave ragged right margins, then spaces have the same value as letters. But, if you go up to the format line and select "justified margins" so the right edge is even, as in a book, then you get differences in the sizes of the spaces between words to make the right margin even. That option is not available on the TOTV format line.
By the way, no "rulemaker" is going to prevent me from doing two spaces after a period at the end of a sentence.