Incorrect!? I would be interested to hear his logic on this. It is a long-established custom, and I don’t think there is any regulation contrary to it.
I think the
General Instruction of the Roman Missal (GIRM) supports him. There is no mention in the GIRM about singing after the Dismissal.
The GIRM #90 says: “The Concluding Rites consist of: a. brief announcements, if they are necessary; b. the priest’s greeting and blessing, which on certain days and occasions is enriched and expressed in the Prayer over the People or another more solemn formula; c. the dismissal of the people by the deacon or priest, so that each may go out to do good works, praising and blessing God; d. the kissing of the altar by the priest and the deacon, followed by a profound bow to the altar by the priest, the deacon, and the other ministers.”
There is no mention of singing anything at the end of Mass. This is in comparison to GIRM #47, which makes mention of singing during the Entrance: “After the people have gathered, the Entrance chant begins as the priest enters with the deacon and ministers. The purpose of this chant is to open the celebration, foster the unity of those who have been gathered, introduce their thoughts to the mystery of the liturgical season or festivity, and accompany the procession of the priest and ministers.”
Likewise, in the more detailed rubrics for the different forms of celebrating Mass no mention is made of singing cf. GIRM ## 166-170, 184-186, 250-251, 272.
The fact that recessional hymns are commonplace does not necessarily them right.
Reference: International Committee on English in the Liturgy and Catholic Bishops’ Conference of England and Wales (2005)
General Instruction of the Roman Missal. London: Catholic Truth Society and Colloquium (ISBN 1 86082 288 6) pp 16, 28, 44-45, 47, 57, 59.