Brady shouldn't give his phone to investigators. The NFLPA attorneys definitely coached him on that. These assistants are not in any Union (that I know of?), and so there's a lot more pressure on them to disclose that. The PA would definitely tell their members "absolutely not, do not give your phone to anybody." It's one thing if it's a criminal case or investigation, it's another thing if it's about footballs being 1 PSI below the league minimum.
I actually think the NFL won't be able to suspend Brady in a way that the NFLPA won't be able to reverse. The report, from the summaries I've seen (haven't read it, just seen the highlights), don't have enough on Brady for something that the NFLPA can't counter. Plenty for fans to draw their own conclusions, but not enough to give a sure suspension.
The team can be charged with tampering footballs, and get a $25k fine, because those two guys are employees of the team. Also, the team can suspend Brady w/ pay (similar to what Adrian Peterson got with Minnesota last year) BUt... it's tough for the league to stick Brady with a suspension when the report is so wishy washy and absent of actual evidence aside from (seemingly) these two guys joking about giving Brady beachballs and rugby balls (which are over inflated)...