That said, vitamin D deficiency is a real thing, and is especially common in as you get older. Vitamin D supplements are also pretty cheap.
It's not unusual to have to make quick decisions with little information. This study is enough to justify making sure that you have enough vitamin D, and probably to take reasonable dosages of supplements. You have to be careful, you can kill yourself with overdosages of vitamin D... it is a hormone and not technically a vitamin.
Vitamin D supplemenation is an easy and cheap thing to do, not harmful as long as you don't overdose, and there is some evidence here that could be helpful. So it is reasonable for the moment to take Vitamin D supplements, at least until we've had time to do more detailed studies.