English isn’t your first language right? “Handful” means any amount you can fit into your hand lol. There is no specific number associated with a handful, it can be literally any number but usually only refers to a small amount of people.
10 top tiers out of billions is definitely a handful. There’s probably more than just 10 too lol.
Kaido was only drawing from subjective experience. The Marines have already captured Kaido and turned him into a lab rat multiple times in the past. Turning Kaido into a lab rat proves that they do not want to kill him, they merely want to experiment on him lol.
"More serious" isn't objectively true given the plot at hand (getting closer to the true history and beating the emperors, the actual competitors, in the race to One Piece as well as whatever Imu is up to and other such plots) or an actual qualification for determining a better story, unless the plot relevance I mentioned is the type of consideration you use. Laboon, DBF, Klabautermann... there's all sorts of silly shit if you really wanna sit here and go on about how there isn't a nostalgia high or double standard at work.
Bro you don't know why its stated. You haven't seen his flashback. They could always hurt him. Once again you thought Youkous couldn't hurt Kaidi when his introduction showed a big ass scar on him. Hurting n killing two different things
Because there's not necessarily a causal relationship here, it's not like you suggest. They wanted to show his deeds entirely and so yonko clashes were mentioned. It doesn't implicate it was them to capture him.