I don't think it is a problem. As Ilikemuppets has already pointed out, the violence in TMS is very cartoony, and Looney Toon-ish, meant to be silly rather than destructive. It's also important to remember that the Muppets are all about heart... they are about togetherness and family and love, which have become cliche bywords but actually have meaning to them.
Exactly. They're violent in the way The Road Runner and Wile E. Coyote were. They blow themselves up, and immerge unscathed. just burnt and dazed. I personally hate when people take cartoon violence so seriously, when there's quite a lot of real world violence to contend with. Of course, since people cannot control that violence, they whine and complain about things that aren't based in reality.
What really confuses me, you can't show guns or gun fire on a kid's show, but walk into a toy store or dollar store, and what's the first thing you see? Toy guns! If people are so concerned about imitating that stuff, why would they turn their heads, and hand them an exact replica?
But as for violent muppets... well, the old Wilkins and Wontkins commercials were chock full of random acts of violence. Cannon shots, puppets eatne by shark puppets... all if they didn't drink Wilkins coffee. And let's not forget the Ideal muppet puppet kermits singing in unison, "So buy us, oh buy us, oh buy us we beg, If you don't buy us, we'll bite you in the leg." which led to "Buy us at once, we're a bundle of Charms." "and if you don't buy us we'll break both your arms."
Of course, this is well before people became ovefly concerned with that stuff. And guess what, we had no shooting rampages from that stuff.