I know that it is common to turn a symbol initially built against you into one which now benefits you

The idea behind using clippy was that when created, it wasn't against you; it was always just there to help, with no alterior motive.

The problem is that to a lot of people, the messaging doesn't feel ant-big tech or anti-capitalist

Seeing clippy is more of a message without a message. It could have been any image, but seeing this one thing everywhere starts to show you how many of us there are and that we are capable of working together to achieve a goal (in this specific case: outreach).