That is incorrect. My skyline was not titled till 2000 and it was one of the earlier ones. Motorex is bringing in more skylines everyday. However, I have heard because the got the legalization process approved early, it is one of the only car that is still allowed to be legalized without converting it to LHD.
Also, you can still legalize JDM cars as long as the have a same year US equivelent. For example importing a 95 rx7 would be fine, but not a 99. You do have to convert it to LHD(and a couple other things such as US emissions) though, but then it can be full street legal. I have also heard of other ways people do it such as disassempling the car in its country of origin, shipping it in parts over here, and then reassembling it as a kit car of sorts leaving it RHD. I do not know if there are mileage limits for this or what other restictions there are.