Highly and very unlikely. New or clueless TJ owners often drive in 4Lo in conditions where they shouldn't like on pavement but it very seldom does any damage.I am fearful that him driving it in 4 Low caused some bigger issues.
The TJ has a known history of bad oil pressure senders causing the oil pressure gauge to stop reading or be grossly inaccurate. I'd simply replace the oil pressure with a good brand replacement, avoid cheap store brands like Duralast.