So, you have reviewed the software? If it's so stupid simple, why did it kill a bunch of people?
There is no lower limit on the complexity of a system required to kill people.
So, you're essentially parroting Boeing's narrative IMO. Yes, they want you to think that the system is 'stupid simple' and it's 'no big deal, just one little fix' because obviously that's good for their business.
Maybe, the system required for safe operation is not so simple, and Boeing is no longer competent enough to create a system. Perhaps the 'stupid simple' system was all they were able to muster.
I'm not sure why you think boeing would lie about it. Or how they'd convince the regulators in two different countries to cover it up since you can see the behaviour by reading the graphs in the preliminary report.