Your gonna burn out
And I believe your gonna have to probably either cut 1st or bulk..
I depends on how intense his HIIT cardio is. He could be fine after a while. First couple weeks will be rough though.
I usually do 20 mins of moderate HIIT cycling M-W, with heavy compound exercises following it (Chest, Back, Legs). Th I play soccer. F I combine Back and Chest, but mainly body weight exercises in addition to abs. Saturday more soccer and then rest Sunday.
I haven't burned out, and I'm also looking to lose weight so I'm intense in the gym but I'm more intense in the kitchen.