It's not tampering because it didn't directly come from anyone specific from the team. "A team source" is ambiguous enough that there is plausible deniability from the team they could say that "the reporter is making it up we never said that" etc.
If Jim Rutherford came out in an interview and directly said "Yeah we like Chris Tanev and we're going to sign him come free agency." That's tampering.
Leaking things through the media or the media reporting on things they may have heard or expanding on parts of information they've received, not tampering.
I beg to differ, but come to the same result.
With the reports are saying Jim Rutherford is willing to give Tanev 5 years, it looks like someone has sent a message he shouldn't be sending.
Otoh, the problem is proving it.
The horrid thing is that it allows a team to tamper. For example, say Rutherford tells some underling to tell some other underling to leak without identification that the Pens are willing to pay Tanev for 5 years. Tanev sees the reports, then gets an offer from the Canucks that is for less term and refuses it because he knows he can do better. Clearly tampering, but almost impossible to prove.