This isn’t the same situation as a baker making a cake for a same-sex wedding. This is blatant anti-gay discrimination. But in Russia he has that right.
The old time American answer, pre civil rights era, would be along the lines of allowing “gays” to open their own bakeries to serve their own clientele.
Better said he has the right to choose who he serves. In the US the gov. tells you who you have to serve.