I’m tempted to poke the bear by posting “if individual bonds are bad, I’m sure Vanguard would not let me buy them” but I guess that would make me a troll.
I also haven't seen any restrictions specifically about posting about individual bonds, either. Posts on individual bonds happens all the time when people discuss things like bond ladders, etc.
When I have seen restrictions, it's usually secondary to specific discussions about individual bonds themselves. For example, no posting about proposed laws or regulations, politics, speculation about what congress might/might not do, economic policies, et al.
In fact, here's the full list. If interested, scroll down to section 4 "unacceptable topics"
https://www.bogleheads.org/forum/rules
Cheers.