These are two sugars derived from food sources that you’ve probably eaten for most of your life. Unless you have a highly unusual medical condition, they shouldn’t harm you at any age. They are ubiquitous (read: so common you don’t even notice them) in countless processed foods.
Oats? Well, they’ll always be healthy. They’ll never be bad for you. But two factors come into play.
Firstly, the theory behind PWO’s is to peak the insulin and amino acid profile in the blood stream at the same time. Oats are fibrous and slow-digesting, so they tend to work against the purpose of the drink.
Secondly, PWO’s are ideally followed by a larger meal about an hour or so after the drink. In theory, oats would fill you up more and may steal some of your appetite for that subsequent meal.
But I wouldn’t get too fussy about such things.
Whey hydrolysate (Surge) is preferred in this situation, and the two sugars (also in Surge) would do a better job creating an anabolic environment than milk and standard issue whey, But your PWO is better than nothing, with or without oats.