I would endorse Jack's reasoning.
The core reason the parliamentary secretary is excluded from the subcommittee on agenda on some committees has to do with the independence of the committee. The committee is independent from the government. It is independent from PMO and PCO, that whole government apparatus. In a majority situation, if you want a committee to have credibility, if you want a committee actually to investigate concerns in the Department of National Defence that are independent of what the government might like to see investigated, you will keep the committee as independent as possible.
Having the parliamentary secretary, with the greatest respect to Chris, on a subcommittee, particularly where we are setting agendas, deciding where and what we will investigate and who we will invite to committee, flies in the face of the independence of Parliament and the independence of its committees.
In some respects, the arguments in a minority government for not having a parliamentary secretary on a subcommittee are even stronger in a majority government. I would urge colleagues who like to recite this mandate business that if they wish to have credibility, if they want this committee to have credibility, it will be as independent as possible, and it starts with the subcommittee.