I don't know if this is
obviously wrong with these concerns but...
“we have qualified our engines to be robust” to such cracks but are “modifying the design to avoid them altogether.” The pending changes “will be part of the final design” for the Falcon 9, he added, “in partnership with NASA to qualify engines for manned spaceflight.”
In other words this might not have been a meaningful safety issue. I am not qualified to judge robust in that context, but this reads like a one sided hit piece and the writer has demonstrated past bias. EX: bulging backlog is not a neutral statement.
The only thing we can say for sure is it has not been an issue in the last 29 flights, so the actual risk must be greater than 0 and less than ~10%.
PS: I would hope they would take even a specific risk at 0.01% per flight as a serious safety concern. But, again without data we don't know if it was more or less than that.