That could work if your shears are good and SHARP. We used a cattle de-horner on the turkeys when we raised them. Much easier than the hatchet since it was my job to hold them. I'm just over 5'2" and didn't weigh much more than 125 when we were raising turkeys. It didn't work well. The de-horner...
Lop its head off and be done with it faster. (If, for religious reasons that's not an option, then slitting the throat could be the next best thing, I guess. But it takes longer for them to die.)