Just checked, the game runs fine without Steam. You can even launch KSP_x64.exe to skip the launcher, if you want.
The most interesting part of the log:
[ERR 10:20:15.181] [SteamManager]: SteamAPI_Init() failed. Refer to Valve's documentation or the comment above this line for more information.
[EXC 10:20:15.185] InvalidOperationException: Steamworks is not initialized.
Steamworks.InteropHelp.TestIfAvailableClient ()
Steamworks.SteamApps.GetAppInstallDir (AppId_t appID, System.String& pchFolder, UInt32 cchFolderBufferSize)
SteamManager.Awake ()
[LOG 10:20:15.218] Loading data opt-out preferences from PlayerPrefs
[LOG 10:20:15.244] Requesting data opt-out preferences from https://data-optout-service.uca.cloud.unity3d.com/[stack of unique parameters]
I always used to launch KSP via CKAN [0] so removing the ability to launch independently of Steam would have killed a lot of utility for me. (CKAN is/was the best mod manager for KSP, handling dependency resolution, config options, multiple mod profiles, compatibility checks, and even mod discovery)
The most interesting part of the log: