If you think so highly of third party lenses I must ask you to buy my Tokina ATX28-70 f/2.8 which although very sharp with my EOS1n and EOS620 cameras it is a nice PAPERWEIGHT on my EOS5Dx cameras.
So except for a case where I bought a Zeiss lens 3rd party is not an option. PERIOD.
Everyone who tries to tell me otherwise, they have to buy my nice Tokina paperweight first.
I was lucky to get rid of 2 Sigma lenses in part exchange in a shop.
I had a Tokina ATX 28-80 f/2.8 and it worked just fine on my 5dII and a 1DIV. While the lens worked fine, the images certainly did not stand up to scrutiny. If I chose to view at normal 35mm print sizes (4x6 or so), it would be OK I suppose. I even sent it back to Tokina and all was normal with the lens.
Not the same exact lens as yours and I haven't looked up the release dates of both.
I also own an EOS 620. First real camera I bought, brand new in 1987. I still have it but haven't used it in a long time. Regrettably, I sold off a minty 50mm purchased at the same time a few years ago.
If your 28-70 is from the late 80's, and doesn't work on camera equipment produced in the 2000's, I can't say that I would expect differently.
I am amazed that, for the most part, Canon EF lenses all seem to work with anything made from inception to present day. The exceptions seem to be current IS lenses mounted to early EF film bodies. As I understand it, the EOS 1-V is the only film body that can use all current specification EF lenses.