No it takes way more than that to bend a stock flywheel. When I took my shitty flywheel off the very first time, it was seized onto the crank because who ever put it on did not put grease on the crank. When we finally got the flywheel to come loose it came off so fast that if it had hit one of us it would have broke are legs. We were actually pushing against the crank so hard with the bearing puller it mushroomed out the end of the crank a lil bit. So what the point is, if a stock flywheel can take that much force without bending(and mine did not) then he will be just fine.
Lightened flywheels are known to do that because again your removing metal not moving it. If you take metal off the wrong parts of the flywheel it weakens them and causes them to break apart like you said. This how ever is not the situation at all.
For it to cause premature breakage it first has to be unbalanced. Ive never seen a machinist move metal to balance a crank, they remove metal to do that. You can move metal on a crank, but as long as the metal is moved the same on each side the weight will remain the same also to counter act each other. A flywheel does not have to be a certain design to be balanced, it has to be equal weight all the way around. In this case the metal around the flywheel has changed shape slightly, but the weight around it has remained the same.