Basically the only way it can be exploited is insta-mining where a coin launches with a far too low diff, and even this can be combated by anticipating it and setting the starting diff higher, or low block rewards early. and even this 'insta-mining' is only really centralized/unfair for a few days, within a few weeks the overall mining reward has diluted the first instamining
Another way to fix this is to just run a centralized node for the first few hundred blocks that calibrates the difficulty of the network based on the orphan rate it encounters and pushes it to clients via an ECDSA signed packet; I haven't seen this implemented yet, but it really should be.
As GHOST is okay with orphans (it includes their work in the tree generated), this should not really be an issue with ethereum