A lawyer for Molson could conceivably file a Motion to Quash the Subpoena, however, he has to argue from what are generally a small range of options to deny or limit the scope of the subpoena. The most common is that the request is unduly broad and thereby is burdensome. This would usually not result in granting the quash, but could secure tightening of the scope of the subpoena. I don't know enough to even guess at the likelihood of limiting the subpoena, but the general assumption in litigation is that at least some portion of a facially relevant subpoena will be granted.
https://twitter.com/dpifke/status/1663665211914481667
Amazon filed to quash his deposition subpoena, but that was apparently because they felt that it was premature without more document production. But from the picture of the order he posted, it looks like the judge has already limited the overall scope.
It also really should be covered by insurance, but in my experience you want your own counsel separate from your insurer's anyways, and specialty legal insurance isn't worth the paper on which the policy is printed. Far cheaper to just apply for a business credit card (or keep the balance on your existing one low enough to cover sudden unexpected expenses like these).
Can't his lawyer go to the judge and have this stopped?