I think its only (some) men who seem to have the issue with boys wearing girls clothes. Our nephew who is 3 went through a phase of loving handbags, so my sil bought him a little one, BIL and DP were not happy and DP spent hours taking the mickey out of BIL for having a child who is obviously going to end up gay I did tell DP afterwards that when / if we have DS of our own he will go through exactly the same phase so shouldn't have been too quick to take the mickey out of BIL as now he will have it all to come. Does any of that make sense, I think I rambled
So YANBU so long as they don't look like girls clothes I don't see a problem. You can always cut the label out if it is pink and sparkly!
DN also went through a phase of loving babies and pushchairs, so SIL bought him a lovely pink pushchair and doll! DN is now only interested in anything to do with elecrical appliances DP and BIL are much happier!!