Cooking Meat for Others
You did the right thing to “blend in”.
It’s not only to show your appreciation, but it’s also to show your kindness:
Even though you did not directly engage on the meat purchase for consumption (and thus perpetuating the cycle), you however did directly get yourself involved in meat consumption by grilling the meat.
In this case, you could have recited the Amitabha Buddha’s name while you were at the grill and dedicated the recitation to those animals. Or purchase a little rebirth plaque on their behalf next time you are at a Pure Land Assembly.
This is called turning hatred into gratitude through kindness, turning potential adversaries into future friends.