The issue is not the numerals. I'm really sick of people saying I'm dense because I can't tell the difference between a 6 and a 9. I can read, obviously, and I'm not dyslexic. I know it sounds like a slam-dunk legal case to say only an idiot would confuse a 6 and a 9, but I doubt a judge would agree.
The issue is those design elements which make the respective logos distinctive. The fact that they're different numbers or letters is not relevant. For example, you can't just take the IBM-style lettering, change the letters, and use that for your logo.