As an English white male in his 20's that qualified for free school dinners at a multi gender, multi race school, I can confirm that this is partially true, however...
There is a huge variance in pupils eligible for school dinners, there were some with single moms from rich neighborhoods, there were others from drug infested shit holes with jobless addict parents. This makes the data a lot less useful.
"The suggestion is because white male poor pupils do worse at school their chances of getting good jobs is reduced."
Doing worse in school and having a bad start in life are not mutually exclusive, my school grades were absolutely worthless, but anyone (yes white males too) if they are bothered enough can get a decent further education, school grades are pretty useless after 18. My best friend didn't even finish school, he went on to do a 1 year university access course at 19 and ended up at one of the top universities in the country and is now very successful. My point being is that, yes we are generally treated like shit in school, but I had so many options after leaving it didn't have much impact on my life.
But this is where it gets messy and where I start to agree with the more with the article...
The white males that were in the same bracket as me that are still doing poorly are the ones with drug addled / alcoholic parents from the really shitty areas. Many were generally taking hard drugs from 14-16+, they don't consider bettering themselves aside from getting a job (of any kind). Through my own experience it's that we we're bombarded throughout school with the notion that we are bad, stupid and would never get decent grades, many of them still hold that opinion about themselves. The help and ability to climb out after was always there, but they either didn't believe they could do it or didn't care at this point. Teachers would constantly be punishing us for things we didn't do and things that we did do were blown way out of proportion, they moved the naughty boys into the lower grade standard classes by the end of their first / second year, the naughty girls stayed where they were and were punished a lot less significantly for similar things. IMO it's a clear correlation that the ones that have done worse in life are males with the worst parents / parental support.
Non whites were generally from better areas and were admittedly better behaved, from my experience it's a mixture of the tendency for boys to be more naughty than girls and whites being from worse areas that initially caused the problem, but the handling by teachers of the situation is what lengthens and worsens the problem.
TLDR: It's not the school grades but own personal development that gets ruined in schools, males have it worse but they are generally worse behaved from the start which causes the problem.