@pnelson and @Faizal_Ali, they are concerned that these marmosets will have much higher functioning brains, which might alter the ethical calculus of their experiments. That’s the unforeseen consequences they fear. There are ethical guidelines specifically on humanizing the brains of animals for this reason.
Of course, a point mutation is going to be stability heritable. That has nothing to do with this.
Their concern is the opposite of @pnelson, that this mutation might be more effective (not less) than they imagine. Perhaps they are wrong but this isn’t evidence for @pnelson’s objection.