I totally get your perspective too: you could swap acceptance and denial. Capitalists accept the justification of the status quo while MLs deny it.
In the context of grieve I think Yogthos' perspective is more fitting: "Denial" is the denial that anything is wrong with the system and "Acceptance" of both facts, that the system is fundamentally flawed and that a pursuit of any idealistic one doesn't bear fruit is the necessary precursor for conducting a sober analysis
That's not how the stages of grief work. The last step is for example that you accept your cancer and see that there ain't nothing you can do about it. When the doctor says you're done, there is no cherry pit pillow that can help you.
That is incorrect. Stages of grief do not only apply to terminal conditions where acceptance is fatalistic.
Say you suffer the loss of a loved one. Accepting that they are gone holds within itself the key to continue your live. Acceptance, plain and simple, is a necessity to deal with reality.
Similarly the acceptance that the capitalist system is inherently "broken" enables us to figure out how to deal with that reality, how to overcome its contradictions.
Denying that many of humanities problems are rooted in capitalism does not. The comparison is valid