If Lionsgate keeps the title, a theatrical release increases the value of said movie for licensing, even if it flops. With how much streamers are cutting down their spending, it was unlikely that any of them would buy the movie outright from Lionsgate, or they wouldn't offer enough to make it worthwhile. Additionally, Lionsgate doesn't have a streaming service of their own that's on the level of their competitors, and from what I've read, they frequently pre-sell foreign distribution rights to their titles to offset production costs. For a $30m production from them, I think it was still worth a shot sending it to theaters.