Thipu1 -- I see absolutely nothing wrong with your question and I, too, would wonder how to handle it.
I'm not quick on my feet, so I probably wouldn't have said anything at the time, but now that I've had a chance to think about it . . .
For the people that brought the tongs to the table . . . Wave down a busser or wait-staff personnel that was near your table and point this out. I'm sure that this would have been taken care of immediately. Bringing tongs to the table, then back to the buffet? No. Any reputable buffet simply would not allow this, if they know about it . . . busy places don't always see everything. KWIM?
For the mixing of the tongs at the buffet? It wouldn't bother me at all because I'm not intolerant of any foods (other than what I don't like the taste of.
But you do bring up a good point about the waffle tongs being used for bacon. There are many people that are bacon intolerant (due to diet, religion or what have you) and vise-versa -- GF people might be able to eat the bacon but not the waffles. In this case, I would talk to management about it, after the fact. Maybe write a letter just to notify them what you saw, you know . . . something to keep them on their toes so they don't get sloppy.
If you were, in fact, a person that doesn't tolerate bacon I think that you would be perfectly fine if you stepped out of line and waved over a staff person in order to ask for new tongs since the same tongs for the waffles were also used for the bacon.
Interesting question, Thipu1. I'm looking forward to other helpful responses. Thanks for posting!