On the other hand, he might be seeking a level of detail that is otherwise impossible without direct observation and recording of Kira's form.
Or, as often may be the case in such things, it's the thought that counts: the simulation won't feel the same unless it has been obtained by violating Kira's privacy.
One thing to consider here is the multitude of cultures and legal systems involved. Virtual material like this would easily cross national borders and be highly legal in some places (i.e. you go to jail for trying to prevent people from freely exploiting images of you) and highly illegal in others. Somebody like Tiron might get his peeping done in free-thinking nation X, and then use the resulting simulation in nation Y where peeping carries an extended death penalty but simulation does not.