LMAO NO. Luigi has an okay low% chain grab on spacies, but otherwise you wont really be getting much in the way of follow-ups off grabs if they're DIing correctly. D-throw and F-throw are for setting up tech chases, and you can get U-throw F-air/D-air at kill percent on bad DI, but thats it lol.
Edit: Just wanted to add that Luigi's damage doesn't really come from his grab game. Your main form of damage and combos are going to come from his normals aka N-air D-smash U-smash U-tilt and down B can also be used situationly. Even then you shouldn't be expecting to get more than 2 to 4 follow-ups at the most, but the high damage output of our moves more than makes up for that.
Edit 2: Two potential spacie throw follow-ups I forgot to mention is U-throw D-smash at low% and D-throw F-smash at kill%, with the latter requiring bad DI.