The term 振り出し is used to refer to a starting point.
In the first panel on the page, we see Fukumaru being carried to the bed, meaning our beloved Ojisama sought him out, picked him up, and carried him to the bed. In the final panel, our devoted Ojisama is following after Fukumaru to do the same again.
For this act, the starting point was when Mr. Kanda first went and got Fukumaru, so now he’s returned (戻る) to (に) the beginning (振り出し).
In English, we’d likely use the expression “Back to square one.”
My take on it: He’s an ideal. The traditional distinguished older gentleman. He has the sort of gentle kindness you don’t see in “today’s generation”. He’s someone they can all look up to. He has it together in life. Nothing gets to him. There’s likely also a bit of distance, where the younger teaches feel he’s unapproachable, because he’s so experienced and they’re (in comparison) just starting out. Yet he doesn’t look down on them. He address them in a polite manner.
逆らう means “to go against” or “to defy”. (We’ll learn this from WaniKani when we reach level 28.)
The potential form of this verb is 逆らえる. Potential means what you are able to do, or can do. So “to defy” becomes “able to defy”.
Finally, ず is sort of like ない. It makes it negative. “Able to defy” becomes “not able to defy.”
(For anyone who thinks they are not familiar with ず, if they’ve completed WaniKani level 10, then they actually do know it. The verb 思わず is covered in that level. Whereas 思う means “to think”, if we add ず, we get the negative 思わず “to not think” or “without thinking”. But you’ll see it listed by WaniKani as “unintentionally”, which is when you do something…without thinking.)