There are some sharpening services that have the right tools to sharpen serrated blades. If you ask around at guild or LQS, you might find one. I have one in Chicago (Northwestern Cutlery) that does it, but it would cost $19 in shipping if you don't live in the area plus $3.50 to sharpen so at that point you may as well just get a new pair of scissors. The shipping cost is really only worthwhile if you are sending several knives/scissors out to be sharpened at once.
I would task him with finding a solution to your now dull scissors... especially since they were in your sewing space. I had to label all my scissors for a while until family members eventually learned the difference between sewing scissors, kitchen shears & paper scissors. Took waaaaaay too long for them to learn, if you ask me.
But eventually they got the hint from all my "annoying" little labels telling them what's what.