Like the title says: Should site-specific feeds be tweeting meta questions?
I say no. It doesn't serve much of a purpose, to be honest.
The twitterbot tends to tweet crap in general, but lets assume that it didn't for a second. It would be more worthwhile to tweet something sysadmin related from the main site than a request to blackhole a tag from meta.
If you feel that there is value to having meta posts tweeted, then I think there should be separate twitterbots/accounts for mains and metas.