You certainly have a low opinion of Texas law enforcement.
But after this incident — maybe your low opinion of Texas LEOs is justified.
Not at all. He remained armed a dangerous, that's obvious. He murdered cops in full view of the public. There was no reason not to kill him as quickly as possible with as few losses as possible. There was nothing about this piece of shit that mitigates what he did, and no need for more cops to die to bring this to an end.