Let $M$ be an algebraic family of isocrystals over a base scheme $R/\mathbb{Q}_p$ (not a rigid analytic space).
The question is: is the set of weakly admissible points (i.e., the points $r\in R$ over which $M$ is weakly admissible) Zariski closed or open (or neither)?
The answer might be very simple and/or well-known, but I haven't been able to figure it out.
Thanks for any help!
