Alucard came because this is fascinating magic, and he'll be watching what he can see of the magic the whole time, including the way it arcs from the candle through Bonnie to Tyler. He was just a spectator, but had anything started to go wrong, he would have spoken up and shared. As it is, it was a pretty rare thing to see someone come back from the dead. And he'd have given Tyler a handshake or hug, etc as Tyler seemed to want. He's fine hugging other people too. He definitely relaxed when it took and Tyler became a real boy again.