This is an absurd characterization that is only used by people who don't understand the difference between science and religion and think that calling someone "anti-science" is a way to avoid debate about their religious views. It's as embarrassing as it is offensive.
They didn't say anything about religion - there are many non-religious anti-science views on the right, like climate denial and wild conspiracy theories. Plus, religious views that guide public policy and contradict science are fair to criticize.
I might be misreading the comment you're responding to, but I think it was describing science as a religion.
The dichotomy of "pro-science" and "anti-science" elevates science to an almost religious stature. Science is fallible, it's very hard to do and just as hard to interpret. It's also not the right tool for a lot of issues.
Increasingly people have been adopting being pro-science as a part of their identity as if science held some ultimate, unquestionable truth. To me it is akin to faith, it's an appeal to a higher authority that is used to shut down debate and paint some opinions as moral and others as immoral.
I suppose pro- or anti-religion isn't completely orthogonal to left vs right politics. Support for a dominant religion is more likely to be found on the right, as a means of social control.
A forum could be seen as left-leaning simply by having a policy that all contributors are equal and should be treated with respect. Desire for equality (of wealth and power) is pretty much the defining left-wing characteristic.
This is an absurd characterization that is only used by people who don't understand the difference between science and religion and think that calling someone "anti-science" is a way to avoid debate about their religious views. It's as embarrassing as it is offensive.