He has his clothes on because he's a fatass now. He let himself get way out of shape, which is aamzing for someone who's supposed to be so disciplined. Anyway, he doesn't want his big belly to be seen on camera.
The Master Seagal is able to bring his bride to a mind numbing explosion of bliss with his enlightened touch to her shuddering body. All the while existing in his own state of sensual mastery.
..that and the C-note he slipped in her g-string, which is what the scene looked like and was probably until the edit we saw.
Actually, Steven seagal did take his clothes off in the scene. What happens is that he did it so fast that it wasn't captured properly on camera, it's between frames 35 and 36 in that scene.
After many decades of practising martial arts he can do stuff like that all the time. In fact, if you have the ability (which you'd have if you'd been a martial arts pratitioner as I am) Seagal is not in the movie half of the time. He spends most of his on-screen time on the phone or asaulting the catering.