No, this is not OK.
You would create difficulties :
- For people who want to go to one of these links.
- And for people who want to skip one of these links.
What about people wanting to go to one of these links ? You would make this difficult for these people. Remember that
tabindex is not only for faster wandering in the form,
tabindex is there for accessibility, some people need it to work properly.
tabindex order and the visual order of the fields must have a minimum of consistency. Imagine a user traversing the form with the Tab key ( ⇥ ). The user is at the CAPTCHA field and wants to go to Register. The user will press Tab three times, expecting to land on the button Register. But, with your trick, this would be broken. The user would be puzzled. By wanting to make registration easier, you would have made it more difficult. Hell is paved with good intentions.
The good approach is simple :
tabindex values in natural order. The users who want to skip the two links will skip them.