In terms of specific dates, I will not argue; however, this timeline has a few problems.
The gap between technical alpha and beta in your scenario is about 6 weeks. The gap from beta to launch is only 4 weeks. This seems strange to me, especially in consideration that they have to receive Xbox, Playstation, and Switch approval to release the game on consoles.
The technical alpha was for 4 days (or so). You also think the multiplayer beta will also be 4 days. This seems odd considering the beta presumably needs more time (To date, only 3 of 7 classes have been tested and 2 of 5 acts).
Then, you have the Blizzard investor call which said second half of the year. In corporate speak this usually means the back end of Q3 at the earliest. If Blizzard really was planning on June 29, then different verbiage would have been used.