Garry's Mod Pointshop2 patch that prevents an item on the ground from overriding loadout assignment.

sv_loadout_assignment.lua

-- pointshop2-master\lua\ps2\modules\weapons
hook.Add( "PlayerSpawn", "InitLoadoutConflictListener", function( ply )
    ply.ps2LoadoutPrimaryAssigned = false;
    ply.ps2LoadoutSecondaryAssigned = false;
end )

hook.Add( "PlayerCanPickupWeapon", "LoadoutConflictListener", function( ply, weapon )  
    -- Prevent pickup until player inventory is loaded.
    if not ply.PS2_Inventory then return false end
    -- Cancel listener if player is spectating or a SpecDM ghost.
    if ply:GetObserverMode() > 0 or ( ply.IsGhost and ply:IsGhost() ) then return end 

    local ps2Primary = ply:PS2_GetItemInSlot( "Primary" )
    local ps2Secondary = ply:PS2_GetItemInSlot( "Secondary" )

    if weapon.Kind == 3 then
        -- Cancel listener if primary is already assigned.
        if ply.ps2LoadoutPrimaryAssigned then
            return
        -- Check if primary slot is empty or if weapon pickup is the same as the primary.
        elseif not ps2Primary or ps2Primary.weaponClass == weapon:GetClass() then
            ply.ps2LoadoutPrimaryAssigned = true;
        end
        return ply.ps2LoadoutPrimaryAssigned;
    end 

    if weapon.Kind == 2 then
         -- Cancel listener if secondary is already assigned.
        if ply.ps2LoadoutSecondaryAssigned then
            return
        -- Check if secondary slot is empty or if weapon pickup is the same as the secondary.
        elseif not ps2Secondary or ps2Secondary.weaponClass == weapon:GetClass() then
            ply.ps2LoadoutSecondaryAssigned = true;
        end
        return ply.ps2LoadoutSecondaryAssigned; 
    end
end )