Interested, most definitely, because the hesitance of her movements were enticing in an entirely different manner than his mistresses. They were wanton, racy, exciting. Sigyn was sweet, lithe; small enough that, even in this form, he would have that heady sensation of power, would constantly be aware of how easily he could crush her. Loki liked that, enjoyed being able to take, and take, and take without any hint of remorse.
But he didn't show his interested. Instead, he opted to draw his hands out from behind his head and settle them palm-up on his clothed thighs. His irises were still black, a dark power overtaking his vision, morphing how he perceived things. Though his perceptions were warped, he still had enough sense to know that Sigyn was as lovely as ever. Not seductive, not sensual... but lovely. He licked his lower lip at the sight, minute by minute a new flash of skin was revealed to him, and he feasted on the sight, his body, his gaze burning.
Quickly, to startle her, to catch her off guard, he brought his hands forward and started to clap - once, twice, three times in slow succession. It was difficult to tell whether or not he was mocking her. His face was blank, empty, the set of his lips denoting impatient agitation. His eyes, however, were black with desire.