Since your speculation is that this is the first time a Pope has ever met the wife of a Muslim King, how about when they meet the Muslim King or has that never happened before either?
No, it’s not speculation.
Heads of State meeting other Heads of State is generally a significant news event, and are therefore reported. I have compared a list of all Queens of Islamic countries since approximately 1961* with list of Popes looking for such meetings. I have found none, except for this current meeting between Pope Frances and Queen Rania of Jordan, and one previous meeting between Pope Benedict and Queen Rania in 2009. I am confident there have been no other meetings between a Pope and any Queen of an Islamic nation, because they would have been reported and come up in the search I did.
Have Popes met Moslem Kings - yes, on numerous occasions. I’ve never seen any indication that any Pope bowed in such an encounter, but I would not be horrified if they had, nor would it breach protocol if they had. But there is a difference between the manners a gentleman is likely to show to a lady, and those that might show to another man.
*I used the 1961 date because it corresponds with the ‘modern’ period of diplomatic relations and protocols being defined under the Vienna Convention.