If this issue limit is caused by the open file limit, this limit can be extended on a per process basis on OS X like on any other unix like OS.
Thranduil:~ ralf$ ulimit -a
core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimited
file size (blocks, -f) unlimited
max locked memory (kbytes, -l) unlimited
max memory size (kbytes, -m) unlimited
open files (-n) 4864
pipe size (512 bytes, -p) 1
stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimited
max user processes (-u) 709
virtual memory (kbytes, -v) unlimited
Thranduil:~ ralf$
I would try to extend the limit (ulimit -n <n>) and execute PixInsight by hand (/Applications/PixInsight/PixInsight.app/Contents/MacOS/PixInsight) --- just to check if this is the root cause for the crash.