Is this a reasonable solution?

            foreach (var content in e.SavedEntities)
            {
                if (content.ContentType.Alias == "ContentContainer")
                {
                    content.SortOrder = 0;
                }
                else
                {
                    content.SortOrder++;
                }

                // Only Publish if already published
                if (content.Published)
                {
                    sender.SaveAndPublish(content, 0, false);
                }
                else
                {
                    sender.Save(content, 0, false);
                }
            }

The above is in a function attached to the "ContentService.Saved" event.

Here is a little snippet I've used in the past to sort home page children:

using System.Linq;
using Umbraco.Core;
using Umbraco.Core.Events;
using Umbraco.Core.Models;
using Umbraco.Core.Services;

namespace Site.Events
{
    public class HomePageSortEvent : ApplicationEventHandler
    {
        public HomePageSortEvent()
        {
            ContentService.Saved += ContentServiceOnSaved;
        }

        private static void ContentServiceOnSaved(IContentService sender, SaveEventArgs e)
        {
            var home = e.SavedEntities.First().Parent();
            if (home.ContentType.Alias.Equals("HomePage") && home.Children().Any())
            {
                var children = home.Children();

                // Some logic to reorder home page children... For example...
                children = children.OrderBy(d => d.Name);

                sender.Sort(children, raiseEvents: false);
                umbraco.BasePages.BasePage.Current.ClientTools.SyncTree(homePage.Path, true);
            }
        }
    }
}

In your case, you'd probably want something like:

using System;
using System.Linq;
using Umbraco.Core;
using Umbraco.Core.Events;
using Umbraco.Core.Models;
using Umbraco.Core.Services;

namespace Application
{
    public class SortEvent : ApplicationEventHandler
    {
        public SortEvent()
        {
            ContentService.Saved += ContentServiceOnSaved;
        }

        private static void ContentServiceOnSaved(IContentService sender, SaveEventArgs e)
        {
            try
            {
                foreach (var content in e.SavedEntities)
                {
                    var parent = content.Parent();
                    if (parent == null)
                        continue;

                    var children = parent.Children()
                        .Where(p => p.ContentType.Alias.Equals(“ContentContainer”))
                        .OrderBy(c => c.Name)
                        .ToList();

                    children.AddRange(parent.Children()
                        .Where(p => !p.ContentType.Alias.Equals(“ContentContainer”))
                        .OrderBy(c => c.Name)
                        .ToList());

                    sender.Sort(children, raiseEvents: false);
                    umbraco.BasePages.BasePage.Current.ClientTools.SyncTree(content.Path, true);
                }
            }
            catch (Exception)
            { }
        }
    }
}

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