Standing after Receiving Holy Communion

In the 1970 General Instruction of the Roman Missal (GIRM), the postures of the people, whether to kneel, sit or stand for the various parts of the Mass are established. Specifically, it stated that the people stand from the end of the Offertory until the end of Mass, except that they kneel down during the Consecration. In the U.S. the approved adaptation is to kneel for the entire Eucharistic Prayer and after the Agnus Dei.

43 ... In the dioceses of the United States of America, they should kneel beginning after the singing or recitation of the Sanctus until after the Amen of the Eucharistic Prayer, except when prevented on occasion by reasons of health, lack of space, the large number of people present, or some other good reason.. Those who do not kneel ought to make a profound bow when the priest genuflects after the consecration. The faithful kneel after the Agnus Dei unless the Diocesan Bishop determines otherwise. 

After Communion. This raised the question in some places whether this meant that upon returning from Holy Communion the people were to stand until all sat down upon completion of the Rite. Early on, in 1974, Rome gave an official interpretation of the rubrics on the period after Communion, which makes the posture an option, in other words, leaving it to the individual communicant. It states, 

After communion they may either kneel, stand, or sit. Accordingly the GIRM no. 21 gives this rule: "The people sit. . .if this seems useful during the period of silence after communion." Thus it is a matter of option, not obligation. The GIRM no. 121, should, therefore, be interpreted to match no. 21: Notitiae 10 (1974) 407.

The new 2002 GIRM similarly states, 

43... They should sit during the readings before the gospel and during the responsorial psalm, for the homily and the preparation of the gifts, and, if this seems helpful, they may sit or kneel during the period of religious silence after communion.

However, some of the faithful continued to complain that they were being required to stand at their place after getting back from Communion. A response received from Rome in 2000 clarified, as follows:

Query: Is it the case that the Congregation for Divine Worship and the Discipline of the Sacraments, by no. 43 of the Institutio Generalis Missalis Romani, [the new 2000 GIRM]  intends to prohibit the faithful from kneeling after the Agnus Dei and following reception of Communion?

Response: Negative. [Congregation for Divine Worship and the Discipline of the Sacraments, Prot. 2372/00/L, 7 November 2000]