Your only option would be to remove some of the offending features. TACACS could be swapped for RADIUS, DHCP relay implemented on another device.
Beyond that, you need to evaluate how exposed you are to malicious actors who could attack you. If you are routing guest traffic through the switch, then you have no control the devices. However if all your traffic is fro enterprise devices, (ie locked down, unable to install unauthorised software) then it is unlikely you could be attacked.
If your organisation values data security, flag these issues with the to show you have evaluated the situation, make a hardware upgrade recommendation and leave it in managements hands. If a security breach occurs as a result of these flagged vulnerabilities, you have done all you can, it will be their head that rolls.
cheers,
Seb.
