Classic STW response in that I haven’t read the link (as it’s blocked from here) but seems a bit of an extreme conclusion from the summary you give.
First thing to ask is what is the baseline risk – i.e. that of having a heart attack at your desk? And then, does doubling that risk by exercising make any meaningful difference to the actual risk you face?
Say it’s a one in three risk, doubling it clearly does matter. But say it’s a (more realistic) one in an hundred thousand, putting that up to one in two hundred thousand doesn’t make any meaningful difference to an individual’s risk does it?
Is increased risk of heart attack the only thing covered in the paper?
What about the other risks and benefits of irregular exercise?
Etc Etc Etc.