Since different licenses all activate the same APPIDs, it's pretty normal to provide a package in parts on SG.

Barring exceptionally rare situations where a developer has something weirdly configured, there's really only a few circumstances where giving in part is an issue:
1: You're looking at a different, regional version of the same game (indicated by having a different store page/steamdb listing; For example, the censored, German version of Wolfenstein games). Note, this really only happens when you've got a censored vs uncensored version of a game.
2: You're looking at a package that seems like it'd be a complete package, but it's actually a remastered re-release (For example, Deponia: The Complete Journey activates as a completely seperate listing from its component games, while providing additional behind-the-scenes content). (Conversely, Van Helsing: Final Cut, while also offering different content, can [or at least could; Not sure if that's still available] be freely activated off the developer's website if you own all component pieces, so it is [or at least was] actually possible to provide all three component games and provide the winner with the correct APPID version of the game.)
3: You've got a license for a different version of the game (ie, un-remastered vs remastered, or a different year's version of yearly packages, as some SEGA IPs [eg, Total War] used to offer, which may offer less content than more recent versions of the package).
4: You've failed to properly provide all the component elements (perhaps due to the developer not listing everything on the package page).

Basically, it's generally not considered to be much of a concern (though it of course doesn't hurt to keep in mind).

That said, it shouldn't be a concern for this giveaway regardless, as any version of GTA IV should auto-upgrade to Complete Edition automatically (see my reply to the gifter, below).

PS: Just an FYI that bans can only occur if you harass staff after already being suspended. Suspension lengths can be viewed at the bottom of this page. Non-Activation is a 5 day suspension so, yeah, confirming the contents of one's win is definitely something winners benefit from keeping in mind.