The point is, it is a little contradictory that novices can come up with such comlicated skills, meanwhile Nen geniuses like Gon and Killua can only come up with the most basic Hatsu out of their category.
It's actually outright nonsense compared to previously established rules. Like even if you become a Nen user and gain massive aura through Contagion, where comes the skill of using aura from? Gon and Killua were trained by a double star Hunter (Biscuit) after already learning Nen through Wing, and still remained scrubs that could only beat a rather average guy (compared to Biscuit/Hisoka/Razor) like Genthru with a dedicated plan.
Could anyone imagine Shachimono Tottino stopping the Phantom Troupe at the Auction House? He's been a Nen user longer than any of these guys...
Genthru is not an average guy. Genthru would can trash most Nenusers, a single Star Hunter like Tzezguerra didnt want to fight him Head on. Its Biscuit, Razor and Hisoka who are just on another level, even compared to most spider.
Killua and Gon being able to beat Genthru (even tho gon was still a little weaker than him and won by strategy) means that they were starting to be high level Nenusers on Greed island. They were not good enough yet to be on netero's strike team, but they were close enough to get there with some additional training.
Morena's followers are not anywhere close to that. There is a big difference between being able to create a neat ability and being a high level Nenusers. These are not completely disconnected, but they are not equivalent either.
Kurapika's mafia team had some pretty annoying abilities. Baise can manipulate people with just a kiss, Basho's ability also seems pretty sophisticated. Yet they were not ligh level Nenusers at that point. Baise just died to franklin's bullets and that has nothing to do with manipulatosr just being weak (elseways it would be easy to kill Illumi).
Low level Nenusrs can have strong, annoying abilities.
And it makes sense for them to go for that if they work in a team. For martial artists like gon and kil it does not make sense to lock themselves into a hatsu too quickly. Kastro did that mistake, creating a hatsu that hurt him ont he long run (even tho he made it work). That is why Gon and Kil learned their Hatsu much later than kurapika. Both Wing and Biscuit thought basics come first to really unleash their potenial. That is Wing taught them ten, ren, zetsu before hatsu (water test) and biscuit taught them shu, ko, ryu and Ken before training their hatsus to be actually useful.
As a martial artist, you need to actually very carefully create a hatsu that makes sense in fighting conditions, which is so versatile that it applies to many conditions and so close to you that you will never be unable to perform it (unlike kastro). And you only get that insight after being a high level nenuser already.
For people like morena's followers or people like kortopi, that does not apply. They are not fighters, they start using their hatsus without training such as biscuits, because their abilities are meant for special circumstances.
Morena's followers have morena as a gudie about what abilities to create. It does not matter if they create something that is a little too much for them (like kastro) as long as they can make it work. Using oath and limitation (like kurapika did to very quickly get a very strong hatsu) or working as a team makes absolute sense for them. They are not anywhere close to being skilled Nenusers in an actual nenfight, but they are not martial artists who have to care about being prepared for everything. They are prepared for the task at hand and create their ablities accordingly, just for these few moments.
Someone like Gon would never choose a limitation like "i can only use this ability in morena's room and only after i accused by opponent of breaking the law", but someone like morena's follower can gain just enough strength to escort someone as strong as nobu out of the room.
There is no esstablished law of nen being broken here. It just seems that way because this arc shifts from martial artists who used Nen for other purposes towards Agents/Soldiers.