His face his already hidden under the blanket - That scene would have been creepy just a glimpse of face has he removes the blanket & he puts back on his mask...
Always remember...Don't be a sucker.
He's toying with her, & Carpenter with us.
...my essential 50 http://www.imdb.com/list/ls056413299/
I don't think he wants his face to be ever seen. But lucky for us Laurie pulls off his mask later.
I love when he puts the white sheet over himself. It's a rare time Myers actually shows some personality and creativity.
-Di