With the position of the retaining pin it would be difficult to hit your thumb. You would need to have your thumb pretty high, pretty much resting on the slide, but it could be possible I guess.
The piece would not be very thick either, so that helps.
As far as the tactical sport sight... its not really shaped to help the two most used ways to rack the slide. Overall I am trying to get these designs to be unobtrusive enough that it wouldn't hinder normal use like drawing from a holster yet still provide more grip when racking the slide.
As far as altering the existing sight, that is what the idea on the bottom right is.
These are just basic ideas, and need/are being refined. I am actually on a third revision... in my head.
But I didn't have mockups of those yet.
The new revisions are a little more refined in final shapes and retaining methods.
The real challenge would be finding someone capable and willing to produce these parts. For that there needs to be a market/interest for them.