There are many who say the BBC did report the truth in this programme, ie that overall, Trump's 70 minute speech incited insurrection exhorting people to fight and storm the Capitol. Such a long 70 minute speech overran the time available for the programme therefore it was edited. picking out parts from being and 50 minutes later towards the end, ie an editing decision, accused of being impartial and corrupt.
Reporting "the truth" on any of Trump's unwieldy, chaotic, whatever adjectives you seek to ascribe, poses challenges for news reporters and broadcasters. Trump has sued the media in the US on many occasions, for reporting decisions he does not like, in an effort to suppress, control, silence, build his authoritarian power base, etc as others have outlined.
On this occasion the BBC has admitted it's editing error.