this should work

code/__DEFINES/__game.dm

@@ -151,6 +151,7 @@
 /// Splits admin tabs in Statpanel
 #define SPLIT_ADMIN_TABS (1<<0)
 #define ADMIN_STEALTHMODE (1<<1)
+#define ADMIN_AFK_SAFE (1<<2)
 
 //=================================================
 
@@ -166,7 +167,7 @@
 
 #define TOGGLES_ERT_DEFAULT (PLAY_LEADER|PLAY_MEDIC|PLAY_ENGINEER|PLAY_HEAVY|PLAY_SMARTGUNNER|PLAY_SYNTH|PLAY_MISC)
 
-#define TOGGLES_ADMIN_DEFAULT (NONE)
+#define TOGGLES_ADMIN_DEFAULT (ADMIN_AFK_SAFE)
 
 // Game Intents
 #define INTENT_HELP 1

code/controllers/subsystem/inactivity.dm

@@ -17,7 +17,7 @@ SUBSYSTEM_DEF(inactivity)
 		return
 
 	for(var/client/current as anything in GLOB.clients)
-		if(current.admin_holder && current.admin_holder.rights & R_MOD) //Skip admins.
+		if(CLIENT_IS_AFK_SAFE(current)) //Skip admins.
 			continue
 		if(current.is_afk(INACTIVITY_KICK))
 			if(!istype(current.mob, /mob/dead))

code/global.dm

@@ -34,6 +34,7 @@
 #define CLIENT_IS_STAFF(cli) (cli?.admin_holder?.rights & (R_MOD|R_ADMIN))
 #define CLIENT_IS_MENTOR(cli) CLIENT_HAS_RIGHTS(cli, R_MENTOR)
 #define CLIENT_IS_STEALTHED(cli) (CLIENT_HAS_RIGHTS(cli, R_STEALTH) && cli.prefs?.toggles_admin & ADMIN_STEALTHMODE)
+#define CLIENT_IS_AFK_SAFE(cli) (CLIENT_IS_STAFF(cli) && cli.prefs?.toggles_admin & ADMIN_AFK_SAFE)
 
 #define AHOLD_IS_MOD(ahold) (ahold && (ahold.rights & R_MOD))
 #define AHOLD_IS_ADMIN(ahold) (ahold && (ahold.rights & R_ADMIN))

code/modules/admin/admin_verbs.dm

@@ -73,6 +73,7 @@ GLOBAL_LIST_INIT(admin_verbs_default, list(
 	/client/proc/cmd_mod_say, /* alternate way of typing asay, no different than cmd_admin_say  */
 	/client/proc/cmd_admin_tacmaps_panel,
 	/client/proc/other_records,
+	/client/proc/toggle_admin_afk_safety,
 	))
 
 GLOBAL_LIST_INIT(admin_verbs_admin, list(
@@ -604,12 +605,21 @@ GLOBAL_LIST_INIT(roundstart_mod_verbs, list(
 
 /client/proc/toggle_admin_stealth()
 	set name = "Toggle Admin Stealth"
-	set category = "Preferences"
+	set category = "Preferences.Admin"
 	prefs.toggles_admin ^= ADMIN_STEALTHMODE
 	if(prefs.toggles_admin & ADMIN_STEALTHMODE)
 		to_chat(usr, SPAN_BOLDNOTICE("You enabled admin stealth mode."))
 	else
 		to_chat(usr, SPAN_BOLDNOTICE("You disabled admin stealth mode."))
 
+/client/proc/toggle_admin_afk_safety()
+	set name = "Toggle AFK Safety"
+	set category = "Preferences.Admin"
+	prefs.toggles_admin ^= ADMIN_AFK_SAFE
+	if(prefs.toggles_admin & ADMIN_AFK_SAFE)
+		to_chat(usr, SPAN_BOLDNOTICE("You enabled afk safety. You will no longer be kicked by afk timer."))
+	else
+		to_chat(usr, SPAN_BOLDNOTICE("You disabled afk safety. You will now be auto kicked by the afk timer."))
+
 #undef MAX_WARNS
 #undef AUTOBANTIME