If you straighten the ring (e.g. in a vice) it will work fine. As David said it just needs to get a signal, and the gap must be within the tolerance.
If the front ring is defective it's also not a big deal, the ABS will simply shut down and the warning light will come on. It will under no circumstances apply the brakes. I have done hundreds of kilometers without the front ABS ring and as soon as you put it back on you the ABS works again normally.
Proud member of the HUSABERG ADVENTURE TEAM!
12 690 Enduro-R, 12 Husaberg FE570, 09 KTM XC-F/ 450 RFS hybrid, 07 KTM 450 SMR, 09 BMW F650GS twin/F800GS hybrid, 03+05 YZF-R6