Something in the post should at least attempt to explain what Tuta is rather than just announcing a new name for something hardly anyone has ever heard of.
The point is not whether it's shady, but to trust (at one's discretion) that they will meet minimum expectations. I would expect a change with such absolutely dramatic consequences to be notified in advance and give users plenty of leeway; the opposite seems like a red flag to me, especially when they had no urgency about it.
It's good that they are now more serious about informing their users, but the first time they did it they were very discreet, not even a mention on their blog. A very unpleasant surprise.
A 6 month window is too short, and applies indiscriminately even to accounts that only use a few bytes. They could just delete the content and deactivate them... well, actually that's what they do, but they demand money to reactivate them ._.