That's correct. Spring failure.I would think if operated by oil pressure it would leave timing chain loose for a moment at start up while oil pressure is built.
I'm also confused as to why a manual chain tensioner would be desirable. I've seen them on Gen 1s and a lot of old skool drag bikes. There must be a video somewhere that explains them. Must be afraid of spring failure with conventional ones.
I have a Honda Superhawk and unfortunately this happens all too often, causing piston to meet valves. Manual tensioners solve the problem. I installed manual tensioners on my Superhawk 15 or so years ago and haven't checked them in ages.
Pretty sure the stock tensioner on the FZ is just spring pressure, not oil.