-I am pretty sure that at a date so close to the marriage of the respective heirs to the throne (the future Kings, not a royal butler), both Royal houses of Denmark and Spain had to deal with their own protocol, security, catering, planning and organisational nightmares (plus other problems I can't think of). I don't think they had the time or the energy to properly prepare for the Norway baptism.
- a baptism, whether you like it or not, is not as high profile as a wedding. It make sense to me that the Royal houses would skip the baptism to concentrate on the princes respective weddings, and their appearances on each other weddings (Felipe came to the danish one, Frederick came to the Spanish one). I just think it was a matter of prioritization, and for me, it a reason good enough