.. But what if the seeker did his best and wasn't guided to Islam due to reasons like when Islam reach him in a distorted way?..
Well, I think that seeker shouldn't stop searching even if Islam reached him in a distorted way ( I believe it is another test for him), his journey is not ended yet... So the sincere seeker should turn to the creator (in most cases I know, seekers follow their fitrah, which makes them sure that there must be a creator) supplicate in humiliation to Him, and ask for guidance...
... The truth is that it is extremely unlikely that a person who is searching for religion won't already have a distorted view of Islam because of preconceived notions that bombards people in the West maligning Islam. Being born a nonmuslim in the West pretty guarantees that the vast exposure to Islam will be portrayed in a negative light.
Yes, I agree...Truth in all times was exposed to different sorts of distortion by its enemies, even during the prophet lifetime, Quraish was spreading lies about Islam and opposed it in several ways, but that didn't make honest people stop listening to the truth to judge it themselves....So I don't believe that the western version of Islam is totally distorted, certainly there are places where non-Muslims can find the truth about Islam. And if there wasn't, I think it is our responsibility for not presenting Islam correctly to them, and we will be accountable for that before Allah.