^This pretty much

A) Castellano, and by extension Nino, did not want ANY fuss or trouble, legal or otherwise, stemming from lower echelon members being involved in drugs, it appears that you were only tolerated doing that insofar as you kicked up the proceeds from it, so the hornet's nest(to put it lightly) that would have been open from a confrontation with the Colombians is precisely why Nino made sure that the cubans/colombians's demands were met to avoid the headache.

B) The Colombians had too much reach in that era for the Italians to just try to retaliate or take them on over a stupid drug ripoff from their own ranks, best case scenario if SHTF would be that whoever was killed from Roy's crew etc would have been killed, and possibly a settlement made through backchannels to make sure the violence didn't explode in NYC.