Actually, no. You are interpreting the RAW to mean this.
In this statement:
The statement about 'the walker' is about the model carrying the DCCW. This is a RAW interpretation. The tolerances for the rules may not be as tight as your tolerances, but this is still RAW.
A RAI interpretation would be that Dreadknights use them as powerfists, which is in the description, not rules, of the Doomfists.