I am not wrong. At least from what I have read AND been told by my LEC reps. That example you used has been refuted by other FAQs. Here is the paragraph. It is pretty clear.

4. Pay Longevity Credit for Furloughees
Upon date of signing, any pilot who is, or previously was, furloughed and whose accrued pay longevity is less than that of pilots hired on or before 5/6/08 shall receive additional pay longevity credit for time spent on furlough, but only to the extent that such credit does not provide a pay longevity date prior to 5/7/08.........

Meaning, if you have more longevity AT UAL than 4.7 years, you will not receive additional credit prior to SLI, but you will not lose the longevity that you have. But please, don't take my word for it. Call your reps or go to a Town Hall Meeting.

Sled

From the FAQs:

This paragraph has nothing to do with SLI. It is only about longevity for pay. Neither pilot group offers a credit for furlough time for pay purposes today. This brings all furloughed or previously furloughed pilots with less longevity than 5/7/08 back to that date for pay purposes right away, rather than waiting for the outcome of the seniority list integration. Without paragraph 4, United Furloughees would enter the SLI process with potentially LESS longevity (but nobody will lose ANY longevity actually earned - the only thing the para. 4 credit can do is INCREASE pay longevity).....

The pre-SLI bump is just an interim step. It takes you up to 5/6/08 pay longevity (only up, your longevity is NEVER decreased). Then, at SLI we will add all the furlough longevity we can, but not so much as would take you past the next senior CAL pilot. That might be zero, but in no case would a UA pilot's longevity be reduced, ever.