They didn’t have a majority on the ER committee. So should they have unilaterally ignored the majority report of the other parties and just ram through their own preference for STV?

They had majority in the House. They chose how the committee was constructed.

I’m really amazed how the people with 44 seats is suppose more responsible for something than the people that had 184 seats.

https://en.wikipedia.org/wiki/Canadian_House_of_Commons_Special_Committee_on_Electoral_Reform#Establishment

The initial proposed structure of the Special Committee was three voting members allocated based on each official party’s seats in the House (six Liberal members, three Conservative members, and one New Democratic member), with a member of the Bloc Québécois and Green Party leader Elizabeth May given additional non-voting seats.[6]

The structure of the Special Committee was criticized by the opposition party leaders, as the government would have possessed a majority of the committee seats and could unilaterally recommend alterations to the electoral system without the support of any other party. Interim Conservative leader Rona Ambrose, the Leader of the Official Opposition, denounced the plan as “stacking the deck”, while Nathan Cullen, the NDP critic for Democratic Institutions, urged the government to reconsider this plan as well. The Green Party and Bloc Québécois additionally objected to their lack of voting representation on the committee.[7]

On June 2, 2016, Monsef announced that the government would support a motion by Cullen to alter the structure of the committee to have seats allocated based on percentage of the nationwide popular vote in the 2015 election and give the Bloc Québécois and Greens one voting seat each on the committee.[8][9] The Liberal caucus on the committee would have in effect only four voting members, as the chair would not vote unless there was a tie.[10]

Further references.

2015 Election results: https://en.wikipedia.org/wiki/2015_Canadian_federal_election

Timeline: https://globalnews.ca/news/3102270/justin-trudeau-liberals-electoral-reform-changing-promises/