It's not even a BB gun. It's an airsoft pistol, and that's not an insignificant distinction. As an analogy, comparing the two is like comparing a steak knife to those dinky plastic knives you can get in a fast food chain. BB guns fire copper pellets with enough force to penetrate a soda can at range. Airsoft guns fire plastic pellets that can maybe break skin at point blank range.It's a BB gun apparently.
However I will say this is stupid on so many levels
1) It's an orange tipped gun, that literally is an indication it's a toy of some kind not a real lethal firearm
2) It was during online lessons
3) they suspended him for it. Like really you're suspending a kid from online lessons because he happened to show a BB gun on video at one point? Like what? Why?
To put it a different way, BB guns are dangerous enough that they follow the "never point at another person rule", but are not powerful enough to be considered effective hunting weapons (indeed, as they're likely to penetrate but not kill, shooting animals with them is considered inhumane). Airsoft guns, by contrast, are actually designed to be safe to shoot at other people. They're very much like paintball guns in that respect (and indeed, share the same "to be safe, wear goggles" guideline).