Such casual racism makes a terrorist strike more, not less, likely. Why don't you try to infiltrate organised crime by hanging around a pizza joint, or drug dealers by hanging out in an inner city basketball court?
By lazily assuming all Moslems are terrorists you isolate the vast majority of law abiding Moslems, making it far less likely that they will approach the police if they suspect something. We need to encourage mainstream Moslems to come forward with information, not alienate them.
Sending a white guy into a Mosque who appears more interested in blowing people up than in learning about the Koran will just develop a siege mentality.