Makes sense to me.  I did some of my own comparisons of AA words, and it seems that Semitic has the larger and more conservative phonology.  We just know so much more about Semitic, Egyptian and Berber than we do about Chadic, Cushitic and Omotic, so I was worried we'd have a bias here.
 
My thoughts: Semitic, being closest to the Nostratic homeland, were the most conservative.  Egyptian and Berber follow.  Cushitic and Omotic seem to have simplified phonologies, possibly from Niger-Congo influence.  (I think there was assimilation of some Niger-Congo ethnicities into conquering AA cultures many millennia ago.)  Nilo-Saharan languages, however, have larger consonant inventories, and Hausa and Chadic in general probably got its implosive voiced stops from NS.
 
After Proto-Semitic and Proto-Berber, I've seen a good number of reconstructed Proto-Chadic roots; it's Cushitic that's pretty tricky since it's split up into a number of groups (East, South etc.).
 
The vowel theory according to Bomhard, I think, was this: the three Nostratic vowel phonemes were merged into a single phoneme, a~@.  Remnants of the vowel o~u are evident in labialized velar and uvular stops (i.e. ko>kwa).  I'm not aware of palatization resulting from lost e~i showing up in AA; that's pretty much a feature in IE (velars and "laryngeals" only) and Uralic.
 
~DaW~
 
[Correction: in a previous post, I stated a theory of an Egyptian origin of Judaism and its child religions.  But I forgot about Abraham's home country being Ur, Lower Mesopotamia...]
From: proto-language
To: nostratic@yahoogroups.com
Sent: Tuesday, June 12, 2001 12:30 PM
Subject: Re: [nostratic] A question on Proto-Afro-Asiatic

Dear Danny and Nostraticists:

----- Original Message -----
From: "Danny Wier" <dawier@...>
To: <nostratic@yahoogroups.com>
Sent: Sunday, June 10, 2001 6:47 PM
Subject: [nostratic] A question on Proto-Afro-Asiatic


> Well I've been doing more research on PAA, and I've noticed the reconstructions
> I've seen seem to be closer to Semitic, and Proto-Semitic is most like Arabic.
> Is this really because Semitic and Arabic are such conservative languages, or is
> there a bias involved here?

[PCR]
Being human is, unfortunately, being biased to some extent. "Scientists" probably only ever succeed in minimizing the effects of their biases.

Wouldbe scientists who are aware of this sad situation therefore should try as hard as possible not to be unrealistically dogmatic about any conclusion.