Running wire through sole plate and joist at an angle
First off that's an amazing question!

Most codes would frown upon touching the top or the bottom of a joist in this fashion.

That being said it's probably totally fine to make a tiny hole in the manner you are describing. I've seen some awful things done that caused no problems and if I saw your scenario on a job I wouldn't even notice.

edit

2.5" is pretty big I would definitely notice that.