I won't fix this. There are some problems here that are not trivial:
1 - to make proxies always "safe", we would need to use func_get_args in every proxy call
2 - because of (1), performance will GREATLY degrade
3 - because of (1), byref parameter passing will be broken
What we could do is introspecting the contents of methods to look for func_get_args usages (requires introduction of a complex parser).
I am closing this - consider opening an issue at https://github.com/Ocramius/ProxyManager/issues instead, so we can analyze if this logic can be improved for 3.x with the replacement of the "simple" doctrine proxies with something more complete.
Also note that https://github.com/Ocramius/ProxyManager/issues/159 could also solve this without the need for complex logic.