I had a shop use a similar "tool" on an Electroforged Stingray (the Midget) that had a mildly bent fork. Worked like a charm and never had an issue after the fact. The shop owner loved the bike and only charged me $5. I'd be more cautious with a bike bent as bad as the OP's, or with a lightweight frame. I doubt heavy frames would have an issue, especially with a lightweight rider who's not into jumping curbs.
