It is weird for someone like Sweet to be against the crack trade because of morals, because he belongs to a criminal organisation whose primary functioning purpose is engage in illegal activities for financial profit and gain. The main reason in real life why the Bloods and Crips have had deadly gang wars with each other for so long is because of control of the crack trade, so the game should have reflected that, not some far-fetched, near fantasy story about one street gang being morally better than the other at the expense of more money and power.
I am perfectly cool with this.
As always, I am only trying to counter by offering an explanation based on the in-game information available behind the circumstances such as this, and because of which I don't find Sweet's objection "weird".
The way I see the use of the term "principles" by Sweet is not really about morality here. It's about protecting your family, since Sweet had already seen the deaths of his moms, homies, and brother under his leadership, and the influence of the Families began to decline further as Ballas started selling drugs. It's not like they were running in profits from other illegal activities either, otherwise the homies would have already gone out of their way to throw Ballas out of business with all kind of weapons like AK's, etc. The gang was at its decline when Carl returned, so it's not really about money, or morals here, as evident from the conversations in the mission 'Cleaning the hood'. Sweet just wanted to concentrate on protecting his turf from anything that could further weaken the gang and ruin them completely, because, according to him - "No crack ever made a gang tight". This decision even resulted into the split of the Family in various "sets", and dealing in drugs would be playing into the hands of Tenpenny, since that's exactly what he wanted in order to throw Sweet out of power and his influence over the decisions that GSF makes.
When Sweet returns to LS after getting freed from the jail in the mission 'Beat Down on B Dup' we can actually see him smoking crack, because he had seen the hood's condition had worsened so much by the use of drugs already, which further supports his "decision" of staying away from drugs was right.
GSF is all that Swete had in his life, and I don't expect him to make any compromise just for the sake of financial gains, which is exactly why I don't find him "weird" for his decision about not engaging in drugs.
I understand what you are saying, but I'm fine with Rockstar's approach to the story, and Sweet's character as well. Had the game featured only LS, then I guess it'd have been not that difficult to include the gang rivalry like Bloods and Crips, since Rockstar wouldn't have to make CJ leave the hood because the story has to take into account multiple cities vs. just one city. At one point in the story development, they were planning to include multiple protagonists, and I guess that would have allowed Rockstar to focus more on gang rivalry in the LS part of the story. I guess due to some creative, or other compulsions the idea of multiple protags couldn't come to fruition.