Oh FFS! Do these people know anything?
Post them this and let the silly b@st@rds chew on it.
Baptism has no standing in Law and is not necessary. It is however a rite adopted by many branches of Christianity that involves a ritual washing away of sins. Some Christians (Salvation Army and Quakers for example) do not believe it to be necessary. Others insist upon it as a condition of acceptance into their particular church (See Anglicans and Roman Catholics as an example). In the latter case there is often a further ritual (Confirmation) involved.
In some sects the baptism involves total immersion in water whilst others are content with only a partial immersion, often a simple pouring of water over the head of the one being baptised. There is actually no need for the presence of a priest and any Christian may baptise anyone who wishes it.
Once you have understood this the simple answer to the question is NO! The Royal Caribbean Line do not themselves baptise anyone but who wants an entire shipping line to baptise anyone? Of course a baptism may take place during a cruise on one of their ships and they would never know. Some cruise ships do carry a priest and if not the captain may be willing to perform the ceremony if he is himself a Christian and if you are desperate to have someone in a uniform to run the show but you can do it yourself if you so wish.