he doesn't have a gpu he has integrated graphics
paired with a really poor cpu and tf2 not working, and i dont think it really looks well for him being able to run it
That's what I thought as well. If you have a GPU then you can still run TF2 even with those specs. A decade-old GPU would be fine when TF2 didn't have all the weapons and hats, but seeing as a lot of those exist today...
OP, if you haven't uninstalled TF2 yet, try a
No Hats mod and see if it lets you run the game. If it does then you can run Gmod fine seeing as it doesn't have the half-a-million hats TF2 has.
When in doubt get Gmod during a sale.