Well Touma noticed his father's appearance didn't change, but Tsuchimikado noticed a different thing and asked Touma not to touch it.

Feng Shui

As a former Professor in Feng Shui, not only did he pick up on what was placed in the house, but also how it was placed, and he certainly knows what this arrangement does - three white tigers in a row facing whatever direction etc.

Still, I don't think Touma's dad is the culprit. The Russian mage just looks too fishy. On the other hand, I think Touya's obession with Feng Shui has gathered positive energy around him in such a way that dispelled the effects of Angel Fall on himself.

If one such as Misha, who knows nothing about Feng Shui, saw the photo, they would automatically assume Touya as the spellcaster, much like Touma did.

"You forgot what Misha tried to do to you when she thought you were the culprit?"

You can look at that in two ways. What doesn't support this theory is how Tsuchimikado didn't clear up Touma's suspicions of his dad if he is in fact innocent. He mentioned there were exceptions such as Touma, but his emphasis was on the spellcaster, implying Touma's thinking was correct.