Beyond the prohibition on chattel slavery, there are none I've ever heard of. There are plenty of rights of various types in people's various TUs, but nothing in canon.
The idea of Imperial "citizens" comes more from the title of that Supplement than anything else.
Better reread your T4 stuff and CT JTAS issues...
there is an implied right to rescue in space - T4 Milieux 0 Campaign, p81,
Signal GK
The Preamble of the Warrant of Restoration includes within the imperial goals, "safe travel among the stars" and "the individual pursuit of personal betterment" both of which can be seen as predicates to later granted rights.
Article I of the Warrant of restoration prohibits Imperial Citizens' Rights from being trampled by any Imperial Member World, and also makes any "... living recognized sentient creature native to or naturalized by any member world, or any living recognized sentient creature swearing fealty to the Imperium directly."
Article VI notes that chattle slavery is flat out prohibited.
Article VII implies some interesting quasi-rights - Extraterritorial properties...
- may not be entered from on world nor exited to the world without the local government's permission
- may not be entered nor exited without the territory's imperial governor's permission
Note that it does not give the governor permission to evict people present, only to hold them there if he chooses. Same for stuff.
And some CT sources also grant rights...
JTAS 14, article
High Justice notes that Imperial crimes get a nine-judge panel.
And... it gives
3. The high justice of the Imperium, intended to prevent revolt against Imperial authority, to keep the peace among member worlds, subsectors, and sectors; uphold the rights of sentient beings; and preserve commerce between worlds, subsectors and sectors. High justice is enforced by the lmperial Navy, Army and Marines, often assisted by the Security Branch of the Operations Office of the IISS.
and later in the article...
Major crimes can be combated by all three levels of law enforcement, and prosecuted by all three levels of court. Violators are sometimes subject to capital punishment.
Major crimes normally prosecuted by local authorities include murder, assault,
robbery, grand theft, illegal use of psionics, forgery, terrorism, and rebellion.
Crimes normally subject to subsector justice include the unlawful introduction of high technology to low technology worlds, the violation of a planetary interdiction, possession and/or use of nuclear, chemical, or biological weapons, and war crimes as defined in the lmperial rules of war.
The prosecutors and high courts of the lmperium concern themselves with crimes that would affect worlds in more than one subsector of the realm. These include the capture, transportation, and possession of slaves, piracy, the murder of Imperial officers, officials, or members of lmperial nobility, theft of lmperial property, treason, and conspiracy to commit treason against the lmperium (note that treason against a planetary government is a local crime).
If it can be prosecuted in an imperial court, it's an imperial crime, which implies a right to be free from being the victim of same.
So there's at least a strongly implied minimal right to integrity of body, property, and public safety.