If he were truly a muhallil in reality and the other were a muhallal lahu, they would not be cursed.

1179 - Issue: He said: "And if a muhrim (one in the state of ihram) contracts a marriage for himself or for someone else, or if someone contracts a marriage for a muhrim or with a muhrima (a woman in the state of ihram), then the marriage is invalid."

In summary, if a muhrim marries for himself or contracts a marriage for another, such as being a guardian or an agent, it is not valid. This is due to the statement of the Prophet (may Allah bless him and grant him peace): "The muhrim shall not marry, nor shall he give in marriage, nor shall he betroth." Narrated by Muslim. If a halal (a person not in the state of ihram) contracts a marriage for a muhrim—by being his agent or guardian—or contracts it with a muhrima, it is not valid because it enters into the generality of the Hadith; for when his agent marries on his behalf, he has indeed married. The Qadi narrated two narrations regarding a muhrim being a guardian for someone else; one is that it is not valid, which is the choice of Al-Khiraqi. The second is that it is valid, which is the choice of Abu Bakr, because marriage was prohibited for the muhrim as it is one of the incitements to intercourse, which invalidates the Hajj, and that does not occur by him being a guardian in it for another. The first is more appropriate due to its inclusion in the generality of the report, and because it is a contract that is not valid for the muhrim, therefore it cannot be valid through him, such as buying game [for hunting]. This issue has already passed in the [Book of] Hajj with a more expansive explanation than this.

1180 - Issue: He said: "And whoever of the two spouses finds in their partner insanity, or leprosy, or..."