I'd imagine the chaps on the ground would be saying something along the lines of 'Perhaps if we'd been more proportionate, we wouldn't still be being pursued for a war crimes trial' had fast air been used in the way suggested...
00 - several problems, not least in terms of ROE. Using the AV-8B as you suggest - or any other fast jet (disclaimer - yes, I know someone will be along shortly to say 'Harrier? Fast?') - in 1993 to provide urban CAS would've been extremely difficult in the environment the US troops were operating; use of CBU would have been regarded as a wildly disproportionate use of force, particularly given the casualties that could've been caused amongst non-combatants.
If air support was needed, then the AC-130 was much better suited to the task. AV-8B in 1993 didn't have the capability to do urban CAS in the way it can today, and of the carrier based platforms of that era, only the A-6 would've perhaps have been able to deliver the effects that the ROE would have permitted.
Even using GBU-12 would've been an issue (see current open source material on how it can be an issue today and the solutions pursued by the US to ameliorate this) - CBUs and rockets would've been right out. Conversely, the relative accuracy provided by the AC-130's weapon systems - even the 105mm would have been in with a chance of getting the LEGAD's tick in the box (see ref above to ROE at Fallujah which were more stringent than those in force in Somalia in 93)- would've been a much better and possibly the only practical solution. Which was, of course, why General Garrison and his team requested them in the first place.