"10.1 Caveats and considerations with form population" contains the following:

'Of the four population modes, .... "Choice selection" and "answer context" can only be done as the user encounters each question because they require a user decision.'

This sounds like it is saying that one cannot fetch in advance the needed information for the choice selection or the answer context, but must wait until the user arrives at that question to query the FHIR server for the needed resources. Unless there is FHIRPath embedded in those queries, there is no reason they could not be run before the form was presented the to user. I think perhaps some other meaning was intended, like the answers for those questions are not filled in until the user makes a selection. If that's the case, some rewording would help.