In talking to some people who think what happened to Terri was right and proper (except for her meddling parents dragging everything out), it seems there's a perception that Terri's supporters are engaging in unfair ad hominem attacks against Michael.
While it is true that Terri's supporters are greatly disparaging Michael's character, it needs to be pointed out that if Michael is a liar, there is no credible evidence of Terri's wishes (it's highly plausible that a liar would find relatives willing to perjure themselves). Those who support Terri's parents aren't trying to overrule Terri's wishes, but instead trying to uphold Terri's real wishes against the fake "wishes" invented by her murderous "husband".