When people do stuff that other people don't like, such as derail a piece of legislation aimed at enslaving women, or point out massive lawbreaking on the part of the government, the exposed parties seek cover.
When there's no argument available for the established powers to use to defend themselves, such as in the Texas theocratic power grab, or the NSA spying scandal, they're forced to attack the messenger, to deflect attention away from the message, which is irrefutable.
This is what led Texas Gov Rick Perry to respond to Wendy Davis's filibuster by saying that she was a teen mother, and is herself the child of a single mother. Thanks for that info, Rick. What it has to do with this Christian antiabortion law you've called another special leg session to try to ram through, I don't know.
It's a sad day when a phallus has no where to go. Those whose dirty secrets have been revealed must either confess, or attack, and the only weapon availabe to them is the ad hominem attack.
And that's why I learned today that Glenn Greenwald was kind of a nasty lawyer, that he owes money to the IRS for which he is in negotiation with them to fix amounts, and that he's not only a homo, but once had an interest in a homo porn studio. That made, you know, homo pornographic videos for homos to watch.
The Ad Hom is such a stupid and pointless sort of attack I don't know why people bother. For one thing, the intensity of an ad hominem attack is a good indicator of how much fear and associated rage the ad hominunculus is feeling.