Looks like it to me. Tough to say without seeing it in hand but that looks like the same type of transparency. Fascinating to me that BGS authenticated it with the language Topps used, even though that really doesn't seem correct. They're probably just repeating what was on Topps' COA, right...
Please do post a photo or scan -- it would be interesting to see.
I read a little more about it and I'm nearly positive that the term "transparency" (which is just an unmounted slide) is what you have. Topps did say transparency several times so that seems right. Here's the description from...
I think this [https://en.wikipedia.org/wiki/Reversal_film] describes what we're looking at -- a 'color transparency' seems more accurate (?).
Topps probably used the term "negative" because most people understand what that is and aren't OCD about crap like I am.
Interesting. I'm not a photography expert but it seems like Topps is mixing their lingo here. They call it a full color "negative" and then a "transparency", which are two different things. If it were a negative, I believe it would look much different, as you noted.
Not taking away from the...
I agree that Ebay's notifications are annoying as hell, but I bet they do work on some bidders.
"How bad do you want it?" "Bid more before someone else does!"
I get it. Leave me alone. Ha.