lmao no. lip biting and flashing abs have nothing to do with sexual orientation. In fact, a lot of guys regardless whether they're gay or straight or bi, do this either naturally or acting.
What pings a lot of people's gaydar is his natural reaction to other males contestants which looks like he is crushing on them.
And tbh, his lip biting and flashing abs seem normal for anyone at age 13-15 trying hard to exert that hotness/sexyness (in this case, he's bit of tryhard in trying to pull them off but results showed a lot of people cringed at his attempt). He reminds me of twinks rn who later will grew up becoming older and finally come to terms that they're actually gay.