Firstly, management programs are not open to headhunters to work on most of the time anyway because they are only through direct applications most of the time anyway
Secondly, a good HH will not discriminate base on age, unless the person is only working on one company and one client.
I give you a very good example, last year i was representing a very experienced lady (almost 60 years old), i literally put her in front of 10 companies, as you probably guessed, some companies were put off because of her age, but others did not, and among the 10 companies, 8 actually interviewed her, and she got offered by 4 companies.
And the reason why she didn't get offered by the other 4 companies was not because of age as well, but because they could not afford her asking salary.
A good HH will be working with a lot of different companies and not just 1 or 2 companies.