Injecting to add flavor deep into the meat is a great idea. The pork but is a large cut of meat that can benefit from a good salting.
Keep in mind that You might see streaks or pockets of discoloration from where the marinades pools during cooking. Most marinades do not penetrate very deep below the surface, so they contain oil to help facilitate browning. The spices in the marinade are also too large to be absorbed into the cells of the meat but it can work its way around individual muscles, around the bone, and into any pockets created. To me this wouldn't be a problem, just didn't want it to be a surprise to you. Once you pull the pork these will be distributed evenly, so go for it.
There is nothing wrong with injecting a marinade, just didn't want you to be surprised by the coloring when you pull it apart.