It say's right on the first link you provided right at the bottom about encryption and copy right's.
* Does not copy encrypted or copy protected DVDs. USE OF THIS SOFTWARE TO MAKE UNAUTHORIZED COPIES OF MOVIES AND OTHER CONTENT MAY REQUIRE THE PERMISSION OF THE COPYRIGHT OWNER.
Use of ripping software may contravene the copyright laws in certain countries. Please consult your legal advisor for information on the laws in your country.
So if that's all you have you better find something better to help your "It's perfectly legal" argument
And it say's this in the F.A.Q
Q. Does Popcorn copy CSS encrypted DVD-Video discs?
A. No. CSS is an encryption mechanism used to prevent copying of commercial DVDs. The use of DVD decryption software is illegal in the United States and some other countries. Not all DVDs are CSS protected. Some commercial DVDs, public domain movies, your home movies created with Toast, iDVD or DVD Studio Pro, and content that you have recorded on your set-top DVD recorder are not CSS protected. You can use Popcorn to copy these discs.