More like they were using C, saw the prospect of unbounded stack calls unreasonable with a computer with limited ram and banned recursion. Oh wait that's exactly what happened because iteration is safer than recursion.
Iteration is not inherently safer than recursion. NASA also banned while(true) iteration. The important part is "fixed upper bounds".
"Give all loops a fixed upper bound. It must be trivially possible for a checking tool to prove statically that the loop cannot exceed a preset upper bound on the number of iterations. If a tool cannot prove the loop bound statically, the rule is considered violated."
The static analysis tools have a harder time parsing the upper bounds on recursive functions, and so do the engineers doing the code reviews for similar reasons.
This isn't just a NASA thing. Pretty much any embedded coding standard says the same thing. The JSF C++ standard, and MISRA-C I know both do as well, just off the top of my head.
