In the way it is phrased I would second this. The problem is, that it faults the disabled person for the life problem of those around them (THEY are ruining other peoples life). The discourse never ever blames the disabled person here. Doing so will land you in a bad discussive corner - together with the common argumentation of nazis. Though the question of abortion (as stated by OP) is not as clear cut.
The OP doesn’t say that they have a trademark. For me it sound as they don’t have one. Only a registered domain and the name of the software on github. The letter came on the grounds of the oponnents trademark.