One of the zsh options which changes this behaviour is called CSH_NULLCMD, which seems to suggest it is possible to be csh compatible in zsh.

    $ setopt cshnullcmd
    $ < task >task2
    zsh: redirection with no command

`man zshmisc` and search for "REDIRECTIONS WITH NO COMMAND" for all the gory details :/

Edit: inverted csh compat logic in my head :(