After meeting the Old Willow Deity, Ximen Xueya had personally asked the elder to help him with his memories. As he expected, his memories were sealed by his uncle. This fact didn't surprise him, if there is someone who could lock up his memories there are few who could do so, and only his Uncle Baojun would be able to do it flawlessly without leaving a trace.
Asking the Celestial Willow Tree is the safest method, Ximen Xueya had thought to unsealed his memories. He could also do it on his own, but at present not only his cultivation is sealed, but even his state is too weak. He would have a hard time even if his real capabilities are unlocked. His Uncle Baojun is one of the strongest Gods in all of the realms after all.