Pretty much, given that any decent pthreads implementation will offer an adaptive mutex. Unless you really need a mutex the size of a single bit or byte (which likely implies false sharing), there's little reason to ever use a pure spinlock, since a mutex with adaptive spinning (up to context switch latency) gives you the same performance for short critical sections without the disastrous worst-case behavior.
Some people don't want to block for a microsecond when their lock goes 1ns over your adaptive mutexes spin deadline. That kind of jitter is unacceptable.