By the book, Restricted gear is gear that is not commonly available on the open market. However, that doesn't mean that it is inherently illegal - the book also states that what is/is not illegal varies from sector to sector and even from system to system. This means that some Restricted gear, once somehow obtained by the PCs might be perfectly legal for them to own/operate (possibly with licenses for it), but it might not be legal for them to resell it.
This has come up because my players - a band of law-abiding (and enforcing) bounty hunters - have recently completed a big job for Sienar Fleet Systems (SFS). Rather than the sizable cash bounties that they could have claimed, they spent a Triumph on the Negotiation role to have SFS offer them a brand new Skywatcher-class Scout (value of 120,000 credits, modified to remove the twelve probe droid storage/deployment racks and replace them with six large specimen containers for holding prisoners in stasis).
The players are currently operating an aged Loronar E-9 Explorer that is owned by their guild (and that they have to pay 'rental fees' on), so the idea of a starship that they actually own is attractive to them even if the vessel is only modestly better than what they are currently using. The only catch was that the vessel is Restricted, which had me checking over the rules a bit.
Based on what I've read, and the fact that the Skywatcher-class Scout doesn't really have anything terribly edgy (no proton torpedoes, stealth systems, or turbolasers), I figured that SFS could pull a few strings to grant them a license to own/operate the vessel but not to sell it to anyone that lacks those same license privileges.
Obviously, this wouldn't work for all Restricted items. Some have story reasons (like lightsabers) and some are just flat-out military only (like star Destroyers), but with many of the items, I'm going to allow some wiggle room.