It is very likely not suicide. It is much more likely:
1) GLOC with the P-51 pilot
2) Loss of situational awareness by the P-51 pilot losing visual on the B-17 during the pursuit curve.
3) A medical emergency with the P-51 pilot rendering him unable to control the plane.
In any case it is a tragedy on the personal level for families of all involved and the loss of a national treasure. We have lost two B-17s in recent years. Not that many flyables left.
There were only 4 left flying some 20 years ago when I toured the “909” which itself crashed and burned a while back.
Correction on fighter type, it was a P-63 Kingcobra. That plane has more restricted visibility than a P-51. There is a door for entry on the left side and both sides of the canopy have an arch frame directly to the pilot’s right and left.
That didn’t look like a P-51...
Also, I don’t know how many B-17s we have, but last I heard, there is only 1 B-29 left (Fifi), and we must pray that nothing happens to her.