The section "Spirit Etiquette" page 149 seems to be neglected here.
"Since spirits have been known to share their thoughts openly, this reputation can spread. Any time a conjurer deliberately uses a service to cause a spirit they conjured significant discomfort or disruption, decrease the character’s Reputation by 1."
Yes, this is very subjective. GM's rule will play a strong role here.
In addition a section "Spirit Range", page 148
"Spirits try to stay close to their conjurer. If they get more than (conjurer’s Magic rating x 100) meters from their conjurer, they will try to return within that range unless they have specifically been directed not to."
Could spirits view a conjurer who summons them but sends them away as a conjurer who is a coward and doesn't enjoy the presence of the spirit ? They could, it's very subjective.
My reading on this is that if a conjurer demands from spirits to be personal murderers, or excessively uses spirits for direct combat only, that will have an effect on conjurers reputation. With that in mind, Reputation goes both ways, so "good" spirits would be less keen to aid the conjurer, while "bad" spirits would be super happy to go into material plane and murder bunch of meta-humans. Could continuous summoning of "I win button" spiral the conjurer down the rabbit hole ?
For example loosing spirit affinity, or mentor spirit qualities, "good" spirits could get additional dice pools for resisting.
If a player wants to go that way, sure! Dark arts can be very tempting and there are plenty of toxic and twisted mages who can summon nasty horrors. Will that have further consequences, like exclusion out of magical societies and bounties, and at the same time inclusion into cults and magical terrorism jobs ? Absolutely, it can be an interesting path of role-play exploration.
Yet we can not forget the group and the context in which such a player (character) behaviour occurs! If the whole group is fine to explore the other side of the barricade, that's awesome! Burnouts, toxic adepts, cyberzombie Streetsams or addicted riggers, as far as everyone has fun.
If the group does not want to go that way, there will be a problem between players (and characters) and that has to be solved outside of rules. If people break the game law, there are legal consequences designed by the norms of the society in which such a behaviour occurs. In a role playing game, such norms and consequences for disregarding them should stem from us, the role-playing society, players as well as characters.
I don't want to argue against or pro mechanical design of spirit powers, but it seems that it is more about, how to handle a cheesy player who aims to build a character upon constantly exploiting the same tactic. ( Big dice pools of dedicated Conjurers who can than boost attributes to neglect drains thus having super spirits). Rules are allowing it, but the cheese player is not playing alone. There is the GM and there is the group.
I don't propose a solution for everyone, home tables will be easier to handle than convention tables I guess.