I find this thread fascinating and disturbing in equal measure.
I lost my Mum in April 2020 and my DP in January 2022.
I'm 54 and have weathered a few storms, some of which were during my 20s.
At every stage it has been a case of muddling through, sometimes with excellent support from friends and family and work colleagues, sometimes not so much.
My Mum was a very stoic person, in fact a few days before she went into her end stage coma, she made me promise not to "fall apart completely" but only a little bit....
All through my life she was sometimes brutally honest about the fact that bad stuff happens, and while it's ok to have feelings getting through traumatic and shocking experiences is part of - well - life.
It sounds as though the OPs bereaved colleague is trying to do that.
The "advice" colleague sounds like a product of their generation and may be very clumsily well-meaning but also hasn't handled their concerns terribly well.
The clinical quality of their words is what chills me, but you see and read it everywhere, especially on-line, where of course most people look for advice and guidance these days.
Profound grief, especially recent and the trauma that comes with it leaves one very raw, defensive and sensitive and I've had a few experiences where likely well meaning advice has felt like having salt poured into the wound. I felt a real teeth gritting clench imagining how the bereaved colleague might have received those words. From what the OP has described about her management of her own grief, I imagine she might have simultaneously felt belittled and mortified, especially if she has been as discreet as described.
It reminded me of an allegedly close friend who told me to my face how difficult it was being around me in the weeks after my DP died, who had been very helpful and supportive in many ways, but who had also just completed cancer treatment. They insisted on being very involved with my trauma but also needed theirs addressing. Neither of us were equipped for it to be honest and our friendship has now dissolved. Which is sad, but it became very complicated.
Things I have learned -
Bereavement can be like being pregnant. The world and his wife are suddenly experts on the subject, and some are so convinced their perspective is correct they will impose it at all costs, and some will judge harshly if it doesn't match your perspective or progress through the process. All such experiences are unique, and comparisons are fruitless.
Perceptions of grief are paradoxical. I have been simultaneously expected to be a non- functional mess still under the duvet now, and also muscling through warrior style. I'm somewhere in the middle, depending on the day. It takes time, but time is a precious commodity and practical things must be addressed.
The fact that the bereaved colleague is at work is a major thing. The offered support of friends/ colleagues may be exactly what will bolster her through the process.
Advice colleague may well have their own issues, but I think they could have found a better way of handling things if that's the case. If they are just trying to be aware and mindful based on things they have absorbed from the internet that sound good to them, at some point they may have experiences that make them realise humans are complex, messy creatures and sometimes it's not that simple.
Unfortunately traumatic experiences are part of life. A sense of community, being heard, and sharing experiences when appropriate can be so very much more comforting than professional help for some people - but we're all different.
I don't think there is one perfect way of dealing with things like this, but communication is key.
TLDR
Sorry for the trauma dump, this situation resonated with me, and I hope in time everyone involved gains the peace and insight to move forward. It's all very hard.