For this instance "yes".. a solder repair is good, this appeared to be a stress area possible slight tear or puncture. Pin holes caused by the tank rusting from the inside out... I would not recomend this kind of repair. As we all know how new fuel will pull moisture from the atmosphere and if left un attended will condense and settle at the bottom of the tanks.. directly into seams. If a pinhole breaks through, that is gonna be the weakest point of that area. Solder will only "seal" that spot, but what you dont see is the inside, that pinhole area is surrounded by weak metal and it is only a matter of time before it starts giving way.
My partner had a Rebel with a "slight pinhole " leak at the under back side of the tank. I was unaware of this untill AFTER I started welding it. I have a jewlers torch I have used before and used to pride myself on how small a weld would be with minimal touch up or damage.... well this tank decided to prove me wrong... got the welding done, looked great. Added fuel... it started "wicking" through the metal right at the beginning and end of my welds. I continued to carry the welds into what I thought was good parent metal..NOPE..
Long story short, an attempt was made to seal unsung a "chemical liner".. THAT didn't work... he took a cut off wheel and split the tank... it was a mess!!!! The pinch seams were rusted beyond belief.. but the top side of the tank was clean as new...
I'll see if he can locate the pics