What prevents your mast from turning into a missile, should you be involved in a crash?
I tie the mast to a pair of cleats on the cuddy top, by wrapping a short line around the mast and then belaying both ends. If the mast were to slide forward, that loop of line would tighten further, keeping the mast both down and back.
I also wrap my painter around the mast, after belaying it on the foredeck center cleat. That's a backup system (It also serves to secure the end of stays and halyards).
At least two cleats have to rip out before the mast can fly. I'm hoping that's enough. The rear end is secured as well, so add the breaking force of my rear mast support. (However, that's only a 1x4. Might be a reason to beef up that piece - although it's served well in normal use.)
As in the center, I secure the rear by wrapping something entirely around the mast - it's "only" a bungee, but the extra loop will tighten if you try to slide the mast through, whereas a single strap in the shape of a U relies entirely on friction against the support - and in your case that's a roller!
My boom, if an impact were to overwhelm the bungee, would fly only into the cuddy, where it would possibly damage the hull but unlikely to be a risk to bystanders. On your photos, it looks like the boom could travel quite a bit, building up speed, before being checked by the mainsheet. (The mainsheet appears to pull forward, so it would go slack first, if the boom were to move in response to an impact).
The problem with letting it build up speed is that it leads to shock loads on the mainsheet block when it reaches the end of its travel. It also looks it would be free to rotate if a violent enough impact knocked it loose. You certainly don't want the front of it to be able to spear an accident partner as vehicles slide past each other after first impact.
(although otherwise great jousting technique
)
I apologize for the grisly chain of thoughts, but I think, given potential consequences, it's probably worth thinking this through. (Same reason why I use two sets of ratchet straps to hold boat to trailer...)