Yep, ES (and other mainstream names) frequently sell vastly undermounted telescopes. Just because they sell them that way doesn't mean the mount is adequate or will even work correctly out of the box. And I say this as someone who is rather forgiving of mounts for visual.
My ES 127 Mak was not available as an OTA, so I went the cheapest route with an alt/az Nano mount (essentially a freebie.) To nobody's surprise it really isn't a usable combination: a scope with a narrow field of view and RDF, that will be used in the 200x range for planets on a flimsy push mount without any slow motion controls. However, the mount is acceptable for short refractors at lower power.
Anyway, I assume this off topic drift is about a 120mm f/5. Overall length is a bigger consideration for refractors. At 600mm focal length...good luck with that, especially when sporting a 2" diagonal and eyepieces. And as mentioned I wouldn't expect an 80 f/11 to work well either on such a mount. I have an 80 f/11 and the 900mm focal length makes it more sensitive to mounting than an 80ED.