About the political posture of the Committee report . . . all the work was done by "staff" (or very nearly all of it). But there are two types of staffers. One type consists of individuals whose jobs on Capitol Hill are tied to the Representative (in this case, or the Senator), and happen to get assigned to Committee or Subcommittee work for that particular office. Their experience and, where they possess it, expertise is found mostly in managing communications to and from their Congress(person) loyally and without deviation from the office's intended line of approach.
It is the other type of staffer who matters in the context of reports like this. Committees and Subcommittees develop their own separate rosters of staff, up to and including Chief Counsel. These are not quite career civil servants, but the best essentially do conform to that concept of the role.
The 737 MAX report released by the House Transportation and Infrastructure Committee chairman and the Aviation Subcommittee chairman on the 16th is the work of the staff. While obviously the professional (more or less) Committee staffers have party allegiances, their work does tend to be heavily, well . . . professional. This having been said, the report is not endorsed by the Democratic members of the Committee or, presumably, by the professional staff who work with and on behalf of the current "minority".
Maybe I'll have a more thoroughly cynical view about this specific report once I have read it as if it had been produced in discovery by a party adverse to a client, but on present preliminary evidence, the often crazed polarization that dominates political life and public service in the U.S. did not infect the Committee professional staff into political cheap shots or litigation-fanning publicity stunts. Then again, your loyal poster WillowRun 6-3 once upon a time went knocking on Hill doors looking for such a job with an aviation-related committee, even interviewing with the office of the late Sen. Wendell Ford (D-Ky) when he chaired the Aviation Subcommittee of the Senate Commerce Committee, so consider the source, as they say.