First, in the context of CS1, in my experience, the assignments just aren't long enough that speed writing code matters. 20-50 lines of C just isn't that much typing.
Second, in the world of real work, the hard problems rarely boil down to how fast you can get the thoughts out of your head, through the keyboard, and into the computer. I often spend hours or even days pouring over existing code and in the end change a single line of code. If I just started typing right away, I might fix the immediate problem faster, but there's a strong chance I'd end up with a larger diff that makes the code base worse and possibly introduces new bugs and corner cases.
I may be misinterpreting the author; perhaps by "code" he is referring to the full analysis, design, and implementation process, in which case I suppose it is inarguable that a good developer should do this fast (or faster than a poor developer). To a degree he seems to be saying, "start prototyping right away", which is also valuable at times. But still, in either case, what seems odd is the idea that CS1 students ought to already have the skills of an experienced developer. Of course they don't; they're beginning students and the job of the teacher is to guide them to these skills. Perhaps what would be truly helpful here is suggestions of how to improve the curriculum or pedagogy to help students gain these abilities more quickly.