How can any software development methodology be "agile", if the compiler/interpreter has strict rules about acceptable syntax? Since we live in a universe governed by pretty laws of physics, we have to accept that there will always be rules that we're stuck with. We cannot do "whatever we want", we innately accept certain restrictions to our abilities, and work within those restrictions to accomplish our goals and desires.
The goal is understanding what is most important and then putting focus on that. The Agile manifesto intentionally says that the items on the left are more important than those on the right; not that the items on the right are undesirable.
Scrum, likewise, has a strong focus on what is important. Through experience, its creators have written down what they think is most important when developing certain types of products, and left the rest open for their users to fill in.
The key to using Scrum is to start by asking: "Is what I am trying to accomplish the same as what the creators of Scrum meant for it to accomplish, and do I value the same things they do?"
If the answer to both is yes, then you will find that Scrum isn't all that restrictive. It might have rigid rules (though not nearly as rigid as your compiler/interpreter), but those will not bother you much, because they happen to be rules that you should want to follow if you want to focus on what is important.
If the answer is not yes to both, you shouldn't be using Scrum, because you feel constricted. You will be focusing on different things as your rules are, which will lead to conflicts and confusion. This isn't a problem with Scrum not being Agile, but a problem of you using the wrong tool for the job at hand. Remember: people are more important than processes. I'm sure the creators of Scrum would agree with you that you shouldn't use a process that isn't helping you.
It's like cooking. Are you more Agile for throwing some random things in a pot and claiming it's food, or if you find the proper recipe for what you are trying to make and follow it? Only one of the two focuses on what is important. You can claim recipes aren't Agile because they are rigid, but if you focus on what matters, you'll learn soon enough that they are useful regardless. Even if, through experience, you realize the perfect cake requires two spoons of cinnamon instead of one. It's not like the writers are going to bust down your door to force you to follow it.