Like others have said it will be difficult to find a place to live on his own on that kind of salary and have a convenient commute.
If he doesn’t mind sharing there are plenty of places that are not too far that are nice, safe neighbourhoods with good transport links.
My recommends would be
North - Holloway Road (Islington)
Good safe neighbourhood with tube and bus links and close to Kings Cross. All supermarkets close by but lacking decent pubs/ restaurants nightlife.
The Arsenal football stadium is there which is either a good or a bad thing.
North East - Stoke Newington (Hackney)
Nice area with decent accommodation, plenty of good bars and nightlife. Lots of green space and young professionals in the area.
No tube but plenty of bus links and cycle paths down into the city. Also has overground train lines which run into the city.
East - Bethnal Green (Tower Hamlets)
Really good transport links with both tube and bus. Not the cleanest area but there are plenty of bars and restaurants around and close to Liverpool Street. Big supermarkets close to tube station.
South - Bermondsey (Southwark)
Pretty good transport links has tube and bus links to the city. Nice and safe area next to the Thames, not far from Borough Market, Tower Bridge, Maltby Street etc Lots of good food options and this…