The source, who spoke on condition of anonymity, said while they genuinely felt chief executive Cam Wallace wanted to do the right thing, they believed changing the workplace's culture would be difficult.
They told the Herald they felt "completely sick" about how the sexual assault allegations had been handled.
The source thought the company hadn't done enough to address workplace issues when they arose and this had allowed incidents of bullying to occur.
As well as the two instances of sexual assault, other complaints alleged various forms of harassment, inappropriate behaviour, bullying, fat shaming and sexist comments.
MediaWorks did not answer specific questions from the Herald.
A spokesperson last night said the company had "committed to being open and transparent throughout this process and as you know the Maria Dew QC report will be shared with our staff ... before being released to the public.
"The terms of reference are available on our website and cover everything the review has been looking into.
"I will issue a media release [today] which will outline our response to the report and the actions we will be taking as a result."
The source said they believe staff don't trust internal systems and only felt comfortable coming forward because of the external review.
"I think that says a lot, and also makes me wonder how many people haven't come forward because they're too scared and they don't trust in the process."
Current and former workers were asked to come forward on a voluntary basis to share to Dew workplace allegations and evidence.
Dew was to assess that and then make recommendations or refer evidence or allegations which may spark disciplinary employment investigations.
Dew's final report, according to the publicly-released terms of reference, would be provided to Wallace. All participants in the review, as well as current MediaWorks staff and contractors, are expected to be provided with an executive summary of the report.