It is not just a matter of prostrating as you are now trying to say, but a matter of prostrating in the manner described.
I know this is an obvious fact that they do not do this... 1. from having been a Christian myself a very long time ago, 2. having been in the churches of all the main denominations of the Western Church 3. having a reasonable knowledge of the practices of the Orthodox, Coptic and other Eastern churches. it is bizarre that anyone should be arguing over this issue when it is so clear cut and definite that most Christians do not do this.
you are behaving like a troll in arguing over and defending such as silly objection as you made to the brother.