Not to say that it wouldn't work, just that it isn't really necessary - casting a pointer to a structure to a pointer to its first member (and back) is perfectly portable. Perhaps even idiomatic. (Though the casts in that gist seem to be backwards?)
That said, it is 'portable' since in general no compilers reorder the struct members, but container_of is guaranteed to work, works for multiple members in a struct exactly the same way, and will reduce to a simple cast when your offsetof is zero so there isn't any performance penalty in situations like this. IMO there's no reason not to use container_of in this case.
To quote the relevant section (C99 6.7.2.1.13, same wording present in C89):
Within a structure object, the non-bit-field members and the units in which bit-fields reside have addresses that increase in the order in which they are declared. A pointer to a structure object, suitably converted, points to its initial member (or if that member is a bit-field, then to the unit in which it resides), and vice versa. There may be unnamed padding within a structure object, but not at its beginning.
I'll repeat that I consider direct casts to be somewhat idiomatic. Macros are more traditional for offset members.
Or put differently, direct casting comes with an assumption, while container_of doesn't. The fewer obscure assumptions are there in the code, the better. I think we can all agree on that :)