You can turn off image editor for all type of images using web.config.

https://world.episerver.com/documentation/Items/Developers-Guide/Episerver-CMS/7/Configuration/Configuring-episerver-Section/#imageEditor

There is no supported way to turn off images only for one specific type. But I prepared a hack that you could use:

Here is the initializer (that should be registered in module.config):

define([
    "dojo/_base/declare",
    "epi/_Module",
    "epi-cms/command/EditImage"
], function (
    declare,
    module,
    EditImage
) {
    return declare([module], {

        initialize: function () {
            this.inherited(arguments);

            var original = EditImage.prototype._onModelChange;
            EditImage.prototype._onModelChange = function () {
                var result = original.apply(this, arguments);

                if (!this.get("isAvailable")) {
                    return result;
                }

                var target = this._getSingleSelectionData(),
                    canExecute = target && target.typeIdentifier !== "alloytemplates.models.media.tiffimagefile";

                if (!canExecute) {
                    this.set("isAvailable", false);
                    this.set("canExecute", false);
                }
                return result;
            }
        }
    });
});

My Tiff model looks like this:

[ContentType(GUID = "4D3B327B-4A1C-42ED-9A62-E8D4F925B8F7")]
[MediaDescriptor(ExtensionString = "tif,tiff")]
public class TiffImageFile : ImageData 
{
    public virtual string Copyright { get; set; }
}

That's great! Thanks for the help!