It has become a relatively popular argument among creationists and the "intelligent design" movement (there's no difference, really) to claim that scientists want to brainwash children by teaching only evolution in schools and that they are afraid to teach any alternatives, like creationism. Likewise they say that Christians have no problem whatsoever nor are afraid to teach evolution alongside creationism. (For example, Ken Ham is one of the most prominent figures who likes to make this claim.)
However, like everything else, also this is a blatant lie (even though most of those creationists probably don't even realize it at a conscious level.)
In fact, these creationists are afraid to teach what the theory of evolution really says and what exactly its claims are. Creationists are not afraid to teach their own interpretation of evolution, which is most often just a caricature and a straw man. Or, at the very least, they have to make sure to append every single claim with a refutation that they have come up with (and of course ignoring the scientific responses to said refutation.) They can never teach evolutionary theory in an academically and scientifically accurate manner without bias, without their own distortions, caricatures or made-up objections that make sure to "poison the well" (as per the argumentative fallacy with that name.)
Creationists are very much afraid to teach evolution as it is.
Unlike they claim, scientists are not afraid of creationism or teaching it. It's just that its place is not in science class, because creationism is not science (no matter how much creationists claim it to be.) Creationism is not science because it's not testable, verifiable nor, most importantly, falsifiable. The theory of evolution is (again, no matter how much creationists claim that it isn't.) And not only is evolutionary theory testable and verifiable, there exists enormous amounts of experimental results that support it.
Evolutionary theory is the scientific consensus, and for very good reasons, and that's why it belongs to science class, and creationism doesn't. It's not a question of "being afraid."