The Queen had already condensed Ice Essence, so anyone affected by it was as good as dead to her. Only Tang Ye's Flame Essence could melt it. But melting Ice Essence had to be done very carefully, otherwise one could be killed by the high temperature. Therefore, unless it was someone as proficient in controlling fire as Tang Ye, it couldn't be achieved.
More precisely, it was Tang Ye's past life that could accomplish this. Tang Ye, now living in the Great World, was firstly restricted by the destiny of the Great World and secondly had not awakened the memories and power of his past life, so it was impossible for him to control the power of Flame Essence properly. That meant he had no way to defeat the Queen.
Of course, if the Queen exerted her full strength, she would disrupt the destiny of the Great World, drawing the interference of the Warding Barrier's guardians. But since she was here to execute the Xuan Huang plan, she no longer cared about that.
