I'd say that the author missed the chance to add sales copy and/or message the trial users with "Our prices are going up on [date], act now to lock in this rate!"
It seems like you could squeeze at least a temporary bump in conversions out of that.
For most bootstrapped SaaS businesses, the number of active free trial users is so low, it's not worth your mental capacity.
Also. You really don't want customers who will buy from you at $29/mo and won't buy at $39/mo. This is because if $10 makes difference in their purchasing decision, the value they are getting out of your subscription is roughly what you charge. This segment of customers will churn the fastest as they will be constantly on the edge revaluating whether your subscription is "worth it". You might as well not care about whether they become customers or not. So why bother with cheesy tricks to make them convert. It's not worth it.
It seems like you could squeeze at least a temporary bump in conversions out of that.