For two reasons, originally their was a crossover that got cancelled, so the Dev needed to tweak the images a bit, on the other hand, if you read the intro to this game you'll note it says clearly Violet is on a NTS path, I think a number of us were looking at the blowjob and thinking 'this isn't NTS its NTR' at no point had Erik really concented to this escalation, which is why he was clearly shocked by Violet doing it, so it came out as her effectively cheating on him, which isn't NTS, that is NTR. By toning things down to merely 'sucking his balls' it make things more restrained, her pushing her limits but not going too far without Erik's input, those that don't get what the problem was clearly are people that are more interested in the NTR side of the fence rather than NTS, for those that like me that are on the NTS side it clearly was going too far.
I mean seriously people a proper escalation isn't going from being in a exclusive relationship with an individual and jumping straight to dick sucking someone else, its rather going from exclusivity to kissing or depending on people groping, at that point you jump to something like handjob, and afterward you move up to blowjob, the notion is making sure to escalate in a way that is smooth enough to not ruffle the feathers of the couple, you want them to figure their limits and escalate at a comfortable pace. Also typically in a NTS situation you likely want the other partner close by to consent to any escalation, not fucking informing them after the fact, otherwise that is cheating, if Erik had been at the studio and had consented to Violet giving the guy a blowjob, alright, fair enough, but without that its non-consentual, thus NTR.