Tell us about yourself!
With every respect, that is simply not true. It depends greatly on type of engine used yes, but is more dependent on whether or not the engine is internally balanced. 99% of all of these OPE engines are, which means as long as it has some load at the crankshaft/pto end of the engine, it'll be fine. Type of flywheel is irrelevant in this case, as a common retrofit for older engines to gain performance (ie above rated rpm output) is to convert with an aluminum aftermarket flywheel. In the case of what the author has suggested, this setup is fine.