An operator named
-not does not exist in
find. did you mean
-path is an extension found on many
find implementations but not in all.
Your main problem may be that all path name arguments must appear first on the
find command line and if you add a path name type argument past that expanded alias, you get
find arguments in the wrong order.
A general solution for your problem does not exist since you may need to add further
find arguments before or after the path to be excluded depending on the situation.
You may try:
command find "$1̈́" ! -path '*.sync' "$@"
but this only allows one path type argument.