Keep in mind that the grenade portion will still have to be set to one of the trigger mechanisms in the book, which will complicate things. The closest to just "I throw it and then it blows up when I hit them" will still require a Simple Action to arm the grenade for Motion Sensor in addition to the Simple Action to ready the knife, and then the Simple Action to throw it. The same setup is required for Timer, but if he wants to save time, he can have them set up to be Wireless Link, so he can just detonate them with a free action in the same turn. However, then they will need to be toggled to wireless, which either takes a Simple Action, or will need to be done beforehand (meaning the team hacker better have his back and be on a constant vigil lest some punk with a Sleaze Dongle hack his grenades to explode in his pocket, murdering him).
Also, I always include a "GM Beware" mention of how borked the rules for grenades are. Be prepared to break out a calculator as you determine the damage the explosion deals to all surfaces in six directions (up down left right front back) and potentially bounces between them multiple times. A frag grenade thrown in the second-floor hallway of a building would require you to check if it deals damage to the floor, walls, and ceiling, then if they aren't destroyed, have it reflect back and theoretically bounce again if the damage loss is enough for it to not destroy (or potentially not damage) the structure on a second hit, etc. This is also why, for the record, flash-bang in an elevator instantly kills people (because they don't lose damage from distance, and cannot harm objects, but still bounce).