A (very) quick google search suggests this assertion is not true.
It appears that the DOJ has been called in to investigate specific death threats, and other threats of violence against school board members in a few jurisdictions.
Garland announced that the FBI would work with U.S. attorneys and federal, state, local, territorial and tribal authorities in each school district to develop strategies against the threats. “The Department takes these incidents seriously and is committed to using its authority and resources to discourage these threats, identify them when they occur, and prosecute them when appropriate,” Garland wrote in a memorandum issued this week.
Read more at:
https://www.newsobserver.com/news/politics-government/article254840647.html#storylink=cpy
Actual Memo from Garland:
In recent months, there has been a disturbing spike in harassment, intimidation, and threats of violence against school administrators, board members, teachers, and staff who participate in the vital work of running our nation's public schools. While spirited debate about policy matters is protected under our Constitution, that protection does not extend to threats of violence or efforts to intimidate individuals based on their views.
Threats against public servants are not only illegal, they run counter to our nation's core values. Those who dedicate their time and energy to ensuring that our children receive a proper education in a safe environment deserve to be able to do their work without fear for their safety.
The Department takes these incidents seriously and is committed to using its authority and resources to discourage these threats, identify them when they occur, and prosecute them when appropriate. In the coming days, the Department will announce a series of measures designed to address the rise in criminal conduct directed toward school personnel.
Coordination and partnership with local law enforcement is critical to implementing these measures for the benefit of our nation's nearly 14,000 public school districts. To this end, I am directing the Federal Bureau of Investigation, working with each United States Attorney, to convene meetings with federal, state, local, Tribal, and territorial leaders in each federal judicial district within 30 days ofthe issuance ofthis memorandum. These meetings will facilitate the discussion of strategies for addressing threats against school administrators, board members, teachers, and staff, and will open dedicated lines of communication for threat reporting, assessment, and response.
The Department is steadfast in its commitment to protect all people in the United States from violence, threats of violence, and other forms of intimidation arid harassment.
This does not appear to be any kind of "overreach" as was suggested by the OP.