This iOS Safari bug is terrible. Does the IPad support the blink tag? As far as I know you really can't style <input>'s like you can <button>'s. So if you have a <button> with <span>'s that are styled or <img>'s in side that button, <input> is not the way to go. Instead fake it, make your button behave like it has the attribute 'disabled'.
Add a class to your button:
<button class='ipad-disabled'></button>
Then check to see if that button has that class of 'ipad-disabled', If it does, nothing will happen when you click that button:
$('button').on('click', function () {
    if (!$(this).hasClass('ipad-disabled')) {
        doSomething(this);
    }
});
Then when you need the <button> to be enabled remove the 'ipad-disabled' class:
$('button').removeClass('ipad-disabled');