You can talk sternly without telling someone to go and fuck themselves, in as many words. "It's unacceptable to break userspace. I've fixed the issue personall

You can talk sternly without telling someone to go and fuck themselves, in as many words. "It's unacceptable to break userspace. I've fixed the issue personally on this occasion. Look after your area or I'll be forced to find somebody else who can." would suffice