The two situations are different.
Danny Garcia is the reigning, defending, and undisputed Champion of 140. A title he won by defeating Lucas Matthysse in a close, but clear decision victory. Now that he's at that position he's got to remain that dominant force by facing top competition. Anything less than top comp is unnecessary for a fighter alone at the top of the mountain top. Struggling against Juventud Herrera and taking on Jerry Flynn in a meaningless catch-weight, non-title affair is horse manure for a fighter in his position.
Did Matthysse look less dominant in his stoppage against John Molina? Perhaps, but he DID stop Molina, brutally. Do I like the prospects of him facing either Essa Rios or Silver King? No. But he will get a pass by the boxing community. Do you know why?...........
Because he is not the reigning, defending, undefeated, and undisputed Champion of 140. He doesn't even hold a world title.
You would defend a king who doesn't defend his crown? I wouldn't. Not as a fan of the sport nor the individual fighter. This has nothing to do with my stannery of Matthysse, but everything to do with my stannery of boxing. I find it disgusting that someone in the position of Danny Garcia is taking such a nonsense fight. The same way I'd feel if...
-Klitschko beats Pulev and announces his next bout to be with Shannon Briggs

-Mayweather wins and announces his next bout to be with Pablo Cesar Cano

-Andre Ward announces his next bout to be with Badou Jack
There's opposition perceived to be weak for certain fighters depending on their situation, then there's complete bullshyt.......... And Rod Salka is the latter.