There is no evidence that Trump did anything illegal in trying to influence or obstruct the investigation that, let us not forget, was occasioned by a conspiracy among his political opponents both in and out of government. The parameters of that conspiracy are only now themselves being investigated.
If you were framed for a crime you did not commit, would you forgo an opportunity to speak out upon or investigate the source of such baseless charges simply because some might view it as tampering or evidence of guilt?
Of course not. And yet we must admit that impeachment is a political and not a criminal remedy, for which the definition of "high crimes and misdemeanors" was intentionally left vague. Congress is empowered to impeach and/or remove a sitting President, but they are equally susceptible to the social and electoral consequences of such actions.