This way hey are calling malloc() is very common in professional code bases and a safety measure; I’m surprised the author was surprised.
I am not used to that style so it seems odd to me, but I suppose if it was common in a codebase one would get used to it.
I've spent most of my life dealing with C code dating from 1986 and earlier to present day. Once you get used to the stylistic conventions one of the things that falls out is the simplicity even for huge, old legacy code bases. Often little more than grep or etags is sufficient to competently navigate and follow the flow of this kind of code. Simple things are simple: what callstacks can end up here? etc. The code often has the property that if you printed it you'd still be able to navigate it without issue. Given a random page and a line, getting to somewhere would be possible.
In comparison so many modern code bases are just completely incomprehensible without a tool in the form of an IDE (and often still quite challenging with them because even the IDE isn't sure, and so you must resort to runtime analysis). So many "tricks" used which require tools and require the tools to be bug free and robust.
The closest I have come to "pick it up and you can read and understand it without assistive technologies" is Go.