Why did Labour block Anne-Marie Brady’s testimony?

The Herald reports:

Labour MPs on the justice select committee have voted against allowing China politics expert Anne-Marie Brady to make a submission on foreign interference in elections.
National MPs supported Brady, a professor at Canterbury University, giving her view on the issue which is a focus of the committee’s inquiry into the 2017 general election and 2016 local elections.
The eight-strong committee is evenly split between National and Labour MPs and today’s vote against means Brady cannot appear.
National MP Nick Smith, who is a member of the committee, said it was concerning that Labour blocked Brady from making a submission on the critical issue of protecting New Zealand from foreign interference in its democracy.

Even if one doesn’t agree with everything Brady says, she absolutely should be heard by a select committee inquiring into an area she has extensively published on.

Justice committee chairman Labour MP Raymond Huo said the decision to decline Brady’s late request was purely procedural.

There is no way it is purely procedural. Labour MPs would have been instructed by the Government to vote against. Presumably Labour is worried that allowing Brady to testify would upset the Chinese Government.