Yeah, no. Your assertion is invalid.
First off, there is no arbitrary standard of 'if you look like this, you're a Dwarf.' The traits of a Dwarf include eyes with thermographic vision, pointed ears, denser than average mass due to denser muscles and bones, a naturally more resilient immune system, a naturally stronger will and a below average height. Being short is only the most easily noticeable trait of being a Dwarf (which is different from suffering from dwarfism). If you do not have those (or the equivalents for the metavariants), you are not a Dwarf. You were not born with whatever gave them their Dwarfiness. Someone might mistake you for one, maybe. Just because someone is short, has red hair and wears green in Tir Na nOg doesn't mean they're a leprechaun, even if they look like one.
Being a Dwarf, being short and suffering from dwarfism are three very different things. One is a genetic divergence from the human genome, one is just not being as tall as the average member of your race and one is a lack of growth/development due to some form of medical condition.
There is no 'qualifying' for being a race. You either are one, or you aren't. You might not look exactly like one (Human-Looking does exist), but beneath that all, your genes say 'Elf, Ork or Dwarf.' End of story.
Don't forget, white vs black isn't really a race when you get into the genetics of it. There are different races of primates, including human irl, but white/black/asian/etc. is just a phenotype. Meanwhile, in shadowrun, magic has actually changed both the DNA of and retroactively changed the phenotype of human in to elves, orcs, trolls, and even dwarves. The difference between human and dward is pronounced enough in the average member of the genepool to actually call them a different species and ergo race. However, assuming (because I'm not 100% sure if it's canon or how it works) dwarves and other metahumans are capable of cross breading, it doesn't even brake what we understand of specie; we now know that Homo Neanderthal and Sapiens (fyi, that genus then species) interbred which would mean dwarves and human can be fully separate races and still make a viable hybrid.
Does this mean someone can't make himself look dwarven and be a true human; no, and I don't doubt that they could do it to an extent that would even fool doctors and medical equipment into be able to issue a human a dwarven SIN or vice versa. While it is in the realm of possibility, these modifications cost you essence which means that, while you are becoming more of a poser, you are only becoming less human in the process. As much as your try to twist it, lore and mechanics both say that unless you were born something, you can only be superficially something else.
