If you say it is mental health, then the next time the GOP is supposed to do is pass as many laws as possible to guarantee anyone who feels depressed, suicidal or fantasies with murder gets the counceling and medication they need to save their life and other's.
Sounds great in practice, though I wonder how many people would actually admit to having violent fantasies if doing so meant involuntary commitment to a government-run asylum.
It does not have to do much about admitting anything.
The profile of those who commit mass murder in school has been already extensibly studied (and continues to be to this day). It would be more a job of looks for those who show the red flags of suffering from mental illnesses like depression, antiexy, social isolation, psychopathy, etc. Engaging those problems with medication and therapy so those affected by mental illness can look forward the future with optimism and hope, instead descending a terrible death spiral where they could end up deciding to take their life or the life of others.
However all of it requires an investement which the GOP does not seem to be eager to pass into law, as they are with relaxing gun regulation. Sounds like a recipe for more murder, in my opinion.