Put your speculation to bed; the "interactive, visual depictions of implied sexual violence which are not justified by context" in Saints Row 4 have been fully detailed in a new Classification Board statement.
In a statement published on Kotaku, the Australian Classification Board described a weapon which caused it to refuse classification to the Volition Inc open world title:
"The game includes a weapon referred to by the Applicant as an 'Alien Anal Probe'. The Applicant states that this weapon can be 'shoved into enemy’s backsides'. The lower half of the weapon resembles a sword hilt and the upper part contains prong-like appendages which circle around what appears to be a large dildo which runs down the centre of the weapon.
"When using this weapon the player approaches a (clothed) victim from behind and thrusts the weapon between the victim’s legs and then lifts them off the ground before pulling a trigger which launches the victim into the air. After the probe has been implicitly inserted into the victim’s anus the area around their buttocks becomes pixelated highlighting that the aim of the weapon is to penetrate the victim’s anus.
"The weapon can be used during gameplay on enemy characters or civilians. In the Board’s opinion, a weapon designed to penetrate the anus of enemy characters and civilians constitutes a visual depiction of implied sexual violence that is interactive and not justified by context and as such the game should be Refused Classification."
There you have it. The report also detailed the drug references which were another factor in the Board's decision:
"The game contains an optional mission which involves the player obtaining and smoking drugs referred to as 'alien narcotics'. Smoking the 'alien narcotics' equips the player with 'superpowers' which increase their in-game abilities allowing them to progress through the mission more easily."
Deep Silver and Volition have elected to modify Saints Row 4 for resubmission - presumably removing or reworking the weapon and drug references. As Australian Classification aficionados may recall, drug references got Fallout 3 into hot water a few years back, and Bethesda responded by changing the names and descriptions of certain in-game substances - not a whopping alteration.
Saints Row 4 is due in August on PC, PlayStation 3 and Xbox 360; the Australian release may be delayed if new code can't be cobbled together in time.
Australia introduced an R18+ ratings category for video games on January 1, 2013, but its standards and strictures were not greatly relaxed beyond those of the existing MA15+ category; instead, the new category is designed to draw a distinct line between material suitable for minors and content restricted to adults only. As such, the Board is upholding policy in refusing classification to material which falls outside acceptable content guidelines - and a weapon which enables the gratuitous depiction of sexual assault seems to come under that heading.