Come on...this is more than that because thoughts and prayers are literally just thinking about something (and even that is nice when you're struggling with something).
I fully support OP in making his own choice about what to do with his hair but I think people are going out of their way a bit to shit on what is an act of kindness.
During treatments people often lose their hair and feel self conscious--these people are basically saying, "we're in this together."
It's an act of solidarity. OP shouldn't be getting shit for not doing it but people in here also shouldn't shit on something that is an act of kindness.
Unless they have a brilliant idea that will cure the manager from cancer then there's not really anything else they can do beyond support the person.
The mocking of thoughts and prayers started because, while nice, shootings aren't something out of our hands and we could easily do something about the stuff that's happening but we alleviate guilt by 'thinking' about it and then changing nothing.