Not at all. It is fine to express your appreciation for other games. While the Forums are centered around Terraria, and brings together people who enjoy Terraria and discussing the game, it doesn't mean that other games can't be discussed. 
Terraria Community Forums
Aurora3500
E X P A N S I O N P A C K
Hecc no. Smash Ultimate is love, Smash Ultimate is life. (I assume, I haven't played it yet.)