Yes, this is a time of identity exploration. Questioning does mean questioning, after all.
However, it is important to support a youth where they are on any given day. Treating a young person’s self-defined sexual orientation or gender identity as “experimental” or a “phase” is an example of anti-gay or anti-transgender bias, and it could be interpreted it as rejection. Research shows the significantly detrimental effects of rejecting a youth’s identity as well as the positive effects of accepting them. Why not accept them where they’re at on their journey?