Which essentially makes him not God. Deism seems self defeating in that way - if there is such thing as a first cause God, then He is Goodness, Existence, etc. He is The Standard, and He lives up to Himself by default.
If there is no standard, there is no God. If there is a standard above God, then God is not God, because for God to be God, nothing can be above Him. If there is no God, there is no standard. The alternatives then are nihilism and benevolent theism, and nihilism has its own problems.
Deism tries to find a middle ground, and at first glance seems tempting, but it ultimately fails exactly because God must be the standard. If you hold omnipotence, then If in fact the claim that if an omnipotent God allows evil then that God must be evil is true, then the deist God is also evil, which is simply a contradiction as what is evil can only be defined by how it compares to a standard, which must be God. If you deny omnipotence, then God isn’t God - it is a consequence of the first cause argument that all things that are are permitted to be so by God.
Or in short, a watchmaker God is no more God than an actual watchmaker - there is no (purely from natural reason, so far as I know) reason why this universe couldn’t have been made by an indifferent being, but if it was then that indifferent being does not have the properties demanded of the First Cause God, and so there must be a first cause God above it (and then you could ask why that God allowed the lesser god to create a world with evil, and if it was a problem when God was the direct creator, it will also be a problem when He is thought to be the indirect creator).
The only way out is to hold that God is omnipotent, and also the perfect standard for what is good, but that we might not understand how that works exactly because we are not the perfect standard for what is good. Which, not exactly surprisingly, is exactly what Christianity teaches. We can ask why evil is allowed, and we can gain some partial insight, even some great insight. But even if we couldn’t or if we don’t like the proposed explanations, it is important to understand that if we are talking about a being so far above ourselves that we only exist because He happens to think it is a good idea right now that we do, and who understands and knows everything that ever was, will, or could be, then we are talking about a being who might have a perspective that motivates Him to act differently than us. That is, just because we can’t see a reason doesn’t mean there isn’t one. And it also doesn’t mean that we won’t grow to understand the reason more later on, even if at the moment we don’t like it. (We are as to God what our rather stupid rebellious teenage selves were to our parents, only more so: we think we know more than we do, that He knows less than He does, and we are constantly surprised to find ourselves wrong on either count.)