There are valid question given the fact that many studies suggest that 70-90% of the World population is Right-handed. Left handed people are for sure a rarity in this world.
The answer to the question posed by the gentleman in my blog is a simple No. There aren't any handwriting traits specific to the left-handed people.
The search for this answer really takes me to the basics of the handwriting analysis which stresses that hands are just a vehicle to write something but the way the strokes gets formed come straight from one's brain. Handwriting Analysis has a basis in neuro-science. In simpler terms, it means that various personality traits are represented by different unique neuro-pathways in one's brains. When we write these pathways gets transmitted into the various strokes via the nervous system.
Now, i may not have used the accurate biological terms to explain this but i do hope that it gives you an idea about the role of the hands in writing. In some literature, one's handwriting is also referred to as "brain-writing" for the reasons mentioned above.