The more i weld, the fewer welds i grind. Still a newbie with a mig and occasionally, my bead wanders off the line or i blow a hole or i just f something up. Grinding (mine, anyway) just ends up removing too much surrounding material. Like sanding two pieces of balsa wood glued with ca adhesive, i always seem to scallop the piece in a couple places. So, i work to weld better so i don't have to grind. Makes the job go a lot faster too! Lol
Angelfire has a great comment.
To the op: listen to the good folks here, they are a wealth of knowledge and really are thinking of your well-being. The weld is ****; cut or grind it out and do it again. Takes maybe an hour to do both? Spent more time arguing about it than it would take to fix.
Edit: I take some of that (about the weld being ****) back. I was looking at it on my phone earlier and now, all blown up on my PC, it doesn't look all THAT bad, maybe a bit funky near the top of the weld in the pic. If it were non-structural, I'd say just clean it up (wire wheel), paint it and forget it, unless you have a good reason to grind. Being that it's a cage, I dunno, I have no experience with those (take the advice of someone who knows what they're talking about). What raises my eyebrow, is, what is going on BELOW that weld.. looks like the pipes aren't aligned, or were over-ground.. or what? I can just imagine a downward force bending that to hell.. or is it just me?