Yeah thats what I was suggesting to the guy it's in the first comment you replied to. I mean it's not 100% necessary but I think he'd be more pleased with the long term steadiness of the install like that it's just not as removable as anchors alone.

Sure but if you want a more permanent installation adding the board will give it a lot stronger attachment to the wall and fill in the 7cm gap between the wall and cabinet to make or more steady.

Replacing 1 brick or a couple lines of mortar isn't really messy. Can be contained with a single drop cloth really. That would only come into play when removing the cabinet though and would apply to your installation method as well. That's the exact method I said would be good for a more temporary installation. Replacing mortar ony comes into play once you remove the cabinet because you'll be left with 2 screw holes in your masonry wall. That's when you fill in the mortar which again really shouldn't be messy at all. If you replace a brick or 2 maybe a drop cloth, if it's just mortar I mean a single glove should be enough tbh.

Does it not have places to screw through from the interior of the cabinet into a wall?

If it does I'd put another 7cm board up on the wall with concrete anchors and construction adhesive then screw the cabinet into that from inside. That would be a pretty permanent installation though.

You could just use concrete anchors into the wall attached to a hook or metal loop just use more than 1 they can fail over time if it's just 1 and it's jostled frequently. That way if you move it just patch the holes in the mortar or replace 1 brick.