Life is the standard. God Himself is the standard in so much as He is Life.
And He is Life and so it isn't wrong to say that God is the standard. The only issue is that the vast majority of people don't get what is meant by that statement. Many, particularly atheists, are ready to pounce on it to say that it is meaningless then to call God good. And in the way most people mean it when they say that "God is the standard.", the atheist is right! If God is the standard, in the way most people mean it, then morality only applies to beings other than God who can be compared to that standard. Worse than that, if God is the standard and one hypothetical day God tells a malicious lie, then suddenly malicious lies become morally good! Yikes!
Life, however, provides an objective standard that avoids this problem. Malicious deception is contrary to the rational principles upon which life depends, regardless of who engages in it. Its moral character (i.e. whether it is good or evil) doesn't change depending upon who tells the lie.
God is necessarily good because He is necessarily rational and necessarily living. His goodness is an expression of what He necessarily IS, rather than an arbitrary consequence of whatever He might choose to do.
One might respond by saying...
"If he is necessarily rational and living then there is no "whatever He might choose to do" that is contrary to what we call "right" and so what's the practical difference?"
That's actually a very good objection! There is, in fact, no practical difference in what God will actually do. The difference is in WHY His actions are righteous. Both positions can affirm that God will never act unrighteously. Both can affirm that God is necessarily good. The disagreement concerns what makes those statements meaningful. If God's actions are righteous simply because God performs them, then saying "God is righteous" tells us nothing about His character. It amounts to saying that God does whatever God does.
I, however, maintain that righteousness has objective meaning. God's actions are righteous because they are consistent with the rational principles proper to life. God necessarily acts in accordance with those principles because He is necessarily rational and necessarily living. The distinction becomes apparent when we ask whether God's actions are good because He performs them or whether He performs them because they are good.
It's the difference between God's identity or authority vs. His necessary nature being what makes something good. Either yields the same practical result, but the philosophical explanation is fundamentally different.