They saw how some groups release great mods even without SDK, and they probably know how easy this game is to mod (compared to most), so they're probably affraid that some group will release a "mod" that would put next STALKER games in question
Map pack v1.2 for your PDAs released!
For any patch version - 1.5.05 - 1.5.07 included!
Ultimate "Main menu mods compilation" v1.1 released, including Helios Spawn menu mod 1.3, Cheat mod 1.03, and all-new Faction Commander 1.6!
Should have no problems with either of the 1.5.05-1.5.07 patches!