[PKFFW]

As she is only asking readers to pay what they think reading it is worth it is reasonable to expect that readers will read it first before paying in order to properly ascertain its value to themselves. I don't know the full story but from the quote you provide she never states the book will be free forever. Further, she never claims to be allowing people to purchase a copy of the work(by donation or otherwise) for their own personal keepsake.

So....

Author posts work and allows people to read it for free.(not own it forevermore for free)
Readers read work
Readers pay what they think reading it was worth, including nothing at all if they so choose.
Author decides to discontinue posting work.

So where's the problem exactly?

Cheers,
PKFFW