(1) SSDs are good for privacy for average users since they are cleaning up dirty blocks in the background.
However, IMO, privacy-conscious users who are running a daily free-space wipe, a conventional hard disk is superior because it guarantees that all dirty blocks are erased. A free-space wipe on an SSD can't guarantee that reserved or remapped blocks get erased.
(2) He says, "Somewhat counter-intuitively, information deleted from certain types of encrypted volumes (some configurations of BitLocker, TrueCrypt, PGP and other containers) may be easier to recover ... if the investigator knows either the original password or binary decryption keys for the volume".
If you delete a file in your encrypted volume (but don't do a free-space wipe inside your encrypted volume), then someone who knows your key could potentially recover that file. But that's always been true -- it's true for both SSD and conventional drives.
What I think the author is saying is that someone who use an encrypted volume doesn't benefit from the SSD's cleaning of dirty blocks in the background because the entire encrypted volume looks like it's in use to the SSD controller.
But I don't see how he concludes that it's "easier". You lose the benefit of the SSD's garbage collection, but to recover a deleted file from inside an encrypted volume (assuming you have the user's key) is neither easier nor more difficult with an SSD vs. a conventional disk.