This is certainly true with both of them being 6'1" (although I wouldn't be surprised to see Shesterkin become 6'2" when he gets here). However, there are lots of good goalies in that size range.
5'11": Halak, Khudobin, Saros
6'0": Hutton
6'1": Quick, Lundqvist, Howard, Allen
6'2": Greiss, Gibson, Fleury, Varlamov, Holtby, Bobrovsky
I can't in good conscience include Casey DeSmith on this list with the other, established guys, but he has been a good backup/timeshare goalie for Pittsburgh two years in a row, and he's 6'0". And there are more guys on the list, this was just from looking at SV% leaders with a minimum of 25 games.
Anyway, the two are definitely a little smaller than average, but it's not like the QB position in the NFL where literally everyone has to be 6'0", with extremely few exceptions. In the NHL as a goalie I think you can do really well for yourself, even if you're not a small forward like Ben Bishop.