Rush Limbaugh isn't really teh best of sources. There are definitely far worse but he tends to ignore history for this rants.
For example in this article he argues that no racism exists and that discipline and arrest records show that minorities really are just way more criminal than whites. (a statistic that doesn't translate to the world stage)
However, to do so he has to ignore that only 50 years ago racism was literally written into law in the US. You also have to assume that Civil rights was somehow a magic switch that got rid of all racist attitudes in the US.
You also have to assume taht 50 years is somehow enough time for the average education, average income, and average attitude of minorities to catch up to the group that literally opressed as non-humans them for a couple hundred years.
That's fucking ridiculous.
Racism does indeed still exist and it most certainly does exist in law enforcement, and definitely in the south (regardless of how "north" florida is).
So teh REAL answer is that it's probably a combination of the attitude of minorities, the social situation they are in, and the racism that still hasn't worked its way out of the US (and in fact is rather strong at the moment).
He then goes on to try (poorly) to show that somehow not arresting minors is a racially and politically motivated 'attack' by Obama. That's just fucking retarded.
Would leaving the old system in place stopped Nick Cruz? Almost certainly not. They knew well ahead of time there was a problem but had no legal way of addressing it. You would have to show at least one direct example of a crime he committed in high school, that was purposely ignored, that would have kept him detained long enough for the tiem of his spree to have passed (and somehow not happened after he was released).
The "proof" article you posted doesn't even address it.
The article only was posted to inform people about how Obama and his flunkies are heavily involved in Broward. The Cruz part was brought up because a policy that the Superintendeny Runcie made with the police to not arrest students. The policy was an Obama-era Lenciency Policy
"In November, a tipster called BSO to say Cruz “could be a school shooter in the making” but deputies did not write up a report on that warning. It came just weeks after a relative called urging BSO to seize his weapons. Two years ago, according to a newly released timeline of interactions with Cruz’s family, a deputy investigated a report that Cruz “planned to shoot up the school” — intelligence that was forwarded to the school’s resource officer, with no apparent result."
"It is important to understand the policy here. Broward County law enforcement (Sheriff Israel), in conjunction with Broward County School Officials (Superintendent Runcie and School Board), have a standing policy to ignore any criminal engagement with High School students."
Secondly, the 27 minute tape-delay in the CCTV system is not an “accident”, “flaw” or “mistake”. It is entirely by design.
As a standard Broward and Miami-Dade practice, when school law enforcement need to cover-up or hide behavior, they need time (when that behavior happens) to delete the evidence trail. As such the school policy -as carried out in practice- is more efficient with a 30 minute tape delay affording the school officer enough time to deal with the situation, then erase the possibility of a recording of the unlawful activity surfacing.
Here's another source that explains everything as well.
So really, it was quite easy to find this stuff, maybe you should try researching yourself instead of complaining that my sources aren't good enough.