I'll still be rooting for Garcia. This match is designed to make Garcia look promising.
I agree if this boxer is a good one and capable of beating Garcia, there will be a postponement, Oscar Dela Hoya keeps cherry-picking opponents for Garcia, Haney wants him so badly but the Golden Boy promotions do not want to kill their cash cow yet if Garcia is good enough and DeLa Hoya trust his fighter they'll go for Tank Davis or Haney but they keep avoiding these two fighters and yet Garcia wants to be the next Pacquiao.
It's quite normal and expected that Oscar wants to build the young man's career first and to cherry pick Garcia's opponents to milk more. As the OP said, this is just an interim fight which is also a part of their deal before Garcia will face Kambosos Jr., so I have no doubts as well that this Emmanuel Tagoe will be defeated by Ryan Garcia, though experienced but will be just a stepping stone.
The question now is, can Ryan Garcia knockout Emmanuel Tagoe?
Haney and Davis are too much for Garcia's strenght, Golden boy has to weigh the options first before risking his pet. Garcia is practically just going to look like a kid who just be bullied. It will like a midget vs Lebron.
Tagoe will be fun at least Garcia will look tough if he defeated Tagoe but will also have an excuse once he lose because Tagoe is an experienced boxer.