If true, then they will likely get no conviction at all. There's no premeditation.
As Everybodi mentioned, pre meditation does not need to have been planned elaborately, nor does it need to have been planned far in advance.
If Theo followed Anderson off the pier and attacked him, then that constitutes pre meditation. This is doubly so if it occurred after Theo initiated a prior confrontation against him.
There is NO WAY a jury trial will result in a 21-year sentence for a Navy SEAL who confronted someone he allegedly witnessed taking pictures of little girls. Not in this Epstein era in Santa Monica (next door to Hollyweird).
Though I highly disagree with "NO WAY"- and the defense may also disagree as they keep asking for delays, I do agree that the defense will present a spin that Theo was attempting to protect children.
Of course, the victim apparently has no criminal record, the purportedly sexual photos were seen by a police man and determined to be non criminal, and Theo had already initiated a confrontation and was told to leave the victim alone. In the absence of other extremely negative elements, my guess is that the spin does not go far with the jury.
Going subjective....
I have been to the Santa Monica pier many times. The place is crowded. It is also has a very long standing "live and let live" vibe- meaning people leave other people alone unless one has very good reason not to.
Spend any amount of time there, and you will see another human doing something you don't like- guaranteed. On one occasion for me, it was the doped street performer in Christ like garb with a blasphemous sign / garbled "jokes". The Moslem couple nearby may well of had stronger negative thoughts. All three of us walked away.
Likewise, weirdos, including annoying ones, are a dime a dozen. Yet, despite the crowds, the weirdos, and some humans doing things to alienate others, people initiating confrontations about anything appear to be very rare.
In this case, a confrontation was initiated for very flimsy reasons (victim was simply taking pictures of people in a very public place where photography is very accepted. The victim was not attempting to converse with the girls, nor was he following from the arcades to the rides, nor was he strangely positioned for say, "up skirt" photos).
My guess is that a local jury is going to give more weight to the fact that a needless confrontation was repeatedly initiated than they will his military service accomplishments or the essentially un-articulated sexual elements.