It's the lack of protein.
PETA is often absurd and ridiculous, more interested in publicity - no matter how negative the result - than actually furthering its cause. For example:
Citing the need to reduce greenhouse-gas emissions, People for the Ethical Treatment of Animals is calling on congressional leaders to give vegetarians a tax break.
In a letter sent Wednesday to House Speaker Nancy Pelosi (D-Calif.) and Senate Majority Leader Harry Reid (D-Nev.), PETA President Ingrid Newkirk stated, “[V]egetarians are responsible for far fewer greenhouse-gas emissions and other kinds of environmental degradation than meat-eaters.”
The letter added that vegetarians should receive a tax break “just as people who purchase a hybrid vehicle enjoy a tax break.”
The flaws are many and obvious, so I won't bother with them here. What's important to remember is that, while every member of PETA is a vegan or vegetarian¹, not every vegan and vegetarian is a member of PETA or agrees with its tactics. Assuming that a dietary choice would automatically align someone with a specific group is intellectually shallow. Just so that's clear, since some commentary doesn't.
Link via To The People, with additional commentary at Hit & Run.
¹ The vegetarian/vegan debate is sometimes abbreviated to veg*n to include both without the cumbersome use of both words. I don't know if PETA has any vegetarian employees or activists, or if everyone is vegan. I assume there are a few vegetarians, which is why I included them.

Comments
Actually, you don't have to be a vegetarian or vegan to be a member of PeTA.
Posted by: Elaine Vigneault | June 3, 2007 09:36 PM
I wouldn't expect a specific requirement, but there are non-vegetarians? Interesting. I guess if there are "vegetarians" who eat fish and chicken, that makes sense.
Thanks for the comment.
Posted by: Tony | June 4, 2007 09:07 AM