[jarman]

1) It can be done without shortening and obfuscating URL

2) Wouldn't call it link shortener, as redirector and target are in same administrative domain.

3) I doubt the possibility of meaningful automated fixing of arbitrary links, beyond redirecting to web archive. Which is not always best option and can be done manually or by browser addon

4) Or redirect 0.1% of traffic to attack page. This functionality should be in trusted location (browser or proxy). Screening as opt-in, especially by one providing link is useless