In a 2013 interview with the Guardian [4], he claims there was not much he could do about the Vdara, as the customer specifically wanted an arc-shaped building; in fact the the City Center development has several sweeping arc forms, like in the neighboring Aria -- but the concavity of the Aria's highrises aren't oriented south to converge the midday sun [5], whereas the Vdara aims them right at the pool deck [2].
For both Vdara and the Walkie Talkie, he claims to have been aware of the phenomenon going into the design but lacked the ability to correctly calculate the impact. Further, if claims are true, for the Walkie Talkie he said: "(...) the original design of the building had featured horizontal sun louvres on its south-facing facade, but these are believed to have been removed during cost-cutting as the project developed." [4]
[1] https://www.reviewjournal.com/news/vdara-visitor-death-ray-s... [2] http://www.dailymail.co.uk/news/article-1315978/Las-Vegas-ho... [3] http://www.businessinsider.com/the-vdara-death-ray-hotel-is-... [4] https://www.theguardian.com/artanddesign/2013/sep/06/walkie-... [5] http://www.openstreetmap.org/#map=17/36.10834/-115.17640