Hi Bobby,
Don’t do it. First of all, they wouldn’t know what you are doing. Protestants don’t genuflect. Secondly, we don’t genuflect to the altar. We genuflect to the presence of the Lord in the Blessed Sacrament in the tabernacle. If the tabernacle is not in the main part of the church, we just bow to the altar.
Thirdly, we do NOT believe that their altar is as sacred as ours because we do not believe that their ministers have the power to consecrate bread and wine. Many non-Catholic Christians only see the Eucharist as symbolic and not really Christ’s body and blood anyway.
Fr. Vincent Serpa, O.P.