Hi Chris! I think Father Alar was saying the woman in the garden with formal clothing on that is not usually considered appropriate for the venue in our culture (it could have been in England in the 1700s where it could have been appropriate) is potentially sinful- not that it would be immodest for reasons of exposure of the usual hidden parts of the body but that immodest can comprise that element of intending to draw attention to the body to arouse lust or the attention to our body in another. When people wear bikinis to Mass, if they had no awareness of being naked or causing lust in another, she would not incur sin but in this culture it would likely be a sin for most of us as we would know it was inappropriate for the venue and likely draw attention to our bodies. Fr. Alar stressed intention in terms of culpability and that we never judge another.