Lionelstore is a Lionel LLC site as you can tell from the link at the lionel.com page. But it does bring up an interesting situation in that as you said it is confusing. Here's a couple of things to consider. Companies must defend their trademarks in order to keep them from being diluted and once that happens they become indefensible.
As for use in URLS this little tidbit from the trademark wiki makes it pretty clear that URLS cannot be "cybersquatted": "In the US, the legal situation was clarified by the Anticybersquatting Consumer Protection Act, an amendment to the Lanham Act, which explicitly prohibited cybersquatting. It defines cybersquatting as "(occurring) when a person other than the trademark holder registers the domain name of a well-known trademark and then attempts to profit from this by either ransoming the domain name back to the trademark holder or using the domain name to divert business from the trademark holder to the domain name holder".[36] The provision states that "[a] person shall be liable in a civil action by the owner of the mark ... if, without regard to the goods or services of the person, that person (i) had a bad faith intent to profit from the mark ...; and registers, traffics in, or uses domain name [that is confusingly similar to another's mark or dilutes another's mark]".[37]"
But more to the point, sure these sites are confusing but do they compete? In other words are they selling competing merchandise? No not really since its Lionel branded products for the most part, but they do compete with LionelStore.com for sure. Its a topic thats a sore point with many sponsors I am sure. Which brings us back to the original concern, is it a real Lionel site or not? Seems to me that Lionel ought to be issuing Cease and Desist orders, if for no other purpose than to defend their trademark.