Interestingly, the public policy clearly states that
Part 3 - Conditions (eligibility requirements) applicable to the principal applicant in Canada
Based on public policy considerations, delegated officers may grant permanent residence to a foreign national who meets the following conditions:
The foreign national
...
g. is not inadmissible pursuant to the Act and Regulations, other than for being inadmissible for financial reasons;
Which means that application can't be refused due to the lack of funds.
I reason that there are two possibilities here:
1) The letter itself comes from generic template and may not reflect actual requirements
2) IRCC is demanding more information, but due to the public policy whatever response you provide can't be used to deny PR, because public policy explicitly states, that financial condition of the applicant can't be grounds for refusal.