That is why I cut and pasted most of the ISO 17021:2011 as it relates to the intent and requirements for the stage 1. People who are familiar with management system standards can assess for themselves the method you described of bundling (part of) stage 1 and stage 2 into 1 activity. They can certainly determine if that method satisfies ISO 17021 or not. By the way, it is not an "opinion"; it is professional judgement supported by two decades of profound involvement in the accredited certification business.
And here is what you quoted from ISO 17021:2011:
The stage 1 audit shall be performed to
a) audit the client's management system documentation;
b) evaluate the client's location and site-specific conditions and to undertake discussions with the client's personnel to determine the preparedness for the stage 2 audit;
c) review the client's status and understanding regarding requirements of the standard, in particular with respect to the identification of key performance or significant aspects, processes, objectives and operation of the management system;
d) collect necessary information regarding the scope of the management system, processes and location(s) of the client, and related statutory and regulatory aspects and compliance (e.g. quality, environmental, legal aspects of the client's operation, associated risks, etc.);
e) review the allocation of resources for stage 2 audit and agree with the client on the details of the stage 2 audit;
f) provide a focus for planning the stage 2 audit by gaining a sufficient understanding of the client's management system and site operations in the context of possible significant aspects;
g) evaluate if the internal audits and management review are being planned and performed, and that the level of implementation of the management system substantiates that the client is ready for the stage 2 audit.
For most management systems, it is recommended that at least part of the stage 1 audit be carried out at the client's premises in order to achieve the objectives stated above.
9.2.3.1.2 identification of any areas of concern that could be classified as nonconformity during the stage 2 audit.
9.2.3.1.3 In determining the interval between stage 1 and stage 2 audits, consideration shall be given to the needs of the client to resolve areas of concern identified during the stage 1 audit. The certification body may also need to revise its arrangements for stage 2.
The portion bolded seems to be something Sidney didn't read.
Somehow it just seems logical that recommended doesn't = shall.
Somehow it seems logical that if a least part must be on site that part can also be off-site.
But maybe I just need a new pair of glasses.