I don’t deem it right to evaluate an IIT solely on the basis of its infrastructure when many new IITs are still operating from a temporary campus. IIT BHU works under the umbrella of BHU and shares its campus with it. Many administrative sanctions require approval from BHU not making it autonomous like other IITs.
As for the infrastructure, it might be getting old but it’s not lacking in any way. All the funds the institute received after conversion from IT to IIT were invested in improving the infrastructure of the institute.
So, it’s wrong to say IIT BHU is not worth being called an IIT just because its infrastructure is old. Rather, think about the heritage and experience it holds.