Yes, it is extremely rude and highly inappropriate to instigate a fight between anyone, regardless of their background or circumstances. Instigating a fight is not only disrespectful but also potentially harmful and dangerous for all parties involved.
Moreover, targeting someone because of their disability, in this case, an autistic girl, is unacceptable and constitutes discrimination. People with autism, like everyone else, deserve respect, understanding, and kindness.
If you have issues or conflicts with your ex's new boyfriend or anyone else, it's essential to address them in a mature and peaceful manner. Engaging in violence or encouraging others to fight is never an acceptable way to resolve conflicts. Instead, consider talking openly and honestly about your concerns, seeking mediation or counseling if needed, or simply distancing yourself from situations that might cause unnecessary drama or harm.
Resolving conflicts through non-violent means and treating others with empathy and respect is crucial in building healthier relationships and promoting a more compassionate society.