Praying with Muslims

So I've got this Christian friend who was in a foreign country with a large group of friendly Muslims. They heard the horn and it was time to stop, drop and roll. The Muslims pulled out their carpet and faced Mecca to pray. My friend decided to drop to his knees like the Muslims and pray to Jesus. After a couple of days of this, he decided he really, really liked it. A couple of his other friends rebuked him. They pointed to the example of Daniel in the Bible who wouldn't bow. Daniel could have bowed and prayed to his God but instead took a stand. Someone mentioned to him that he should abstain from the appearance of evil as Scripture suggests and he shouldn't appear to be a Muslim when he is a Christian. I suggested he make the sign of the cross when he knelt and when he got up. (Of course, I have evangelical friends who don't like making the sign of the cross either -- it's too Catholic for them.) Interesting dilemma.