Nilequeen was kind enough to share some information directly from the publication, Purdy et al, 2011; Earliest Art in the Americas: Incised Image of a Proboscidean on a Mineralized Extinct Animal Bone from Vero Beach Journal of Archaeological Science, 2 June 2011
The main scope was a thorough hi tech forensic research to verify its authenticity, which it passed on all counts.
About the age of 13 ky:
There you go. no new information and no challenging of anything. On the contrary, unless the mentioned references falsify it, there is some evidence that the Mammut americanum
survived the Younger Dryas transition, maybe well into the Holocene, as discussed in this thread
. So theoretically it could be (much) younger. But the mineralization of the bone would oppose that.